NetworkManager not runing

Question

I'm completly new to Linux. On my freshly installed Ubuntu 18.04, I cannot connect to the Internet. After some research I figured out it's because my NetworkManager is not running, so I tried to start it and it returned:

jakub@Jakub:~$ service NetworkManager start

Job for NetworkManager.service failed because the control process exited with error code.
See "systemctl status NetworkManager.service" and "journalctl -xe" for details.

So I went for the service status:

jakub@Jakub:~$ systemctl status NetworkManager.service

NetworkManager.service - Network Manager
Loaded: loaded (/lib/systemd/system/NetworkManager.service; enabled; vendor p
Active: failed (Result: exit-code) since Mon 2019-01-21 15:28:23 CET; 1min 7s
Docs: man:NetworkManager(8)
Process: 2273 ExecStart=/usr/sbin/NetworkManager --no-daemon (code=exited, sta
Main PID: 2273 (code=exited, status=1/FAILURE)

sty 21 15:28:23 Jakub systemd[1]: NetworkManager.service: Service hold-off time 
sty 21 15:28:23 Jakub systemd[1]: NetworkManager.service: Scheduled restart job,
sty 21 15:28:23 Jakub systemd[1]: Stopped Network Manager.
sty 21 15:28:23 Jakub systemd[1]: NetworkManager.service: Start request repeated
sty 21 15:28:23 Jakub systemd[1]: NetworkManager.service: Failed with result 'ex
sty 21 15:28:23 Jakub systemd[1]: Failed to start Network Manager.

Any thoughts how to handle it? Thanks in advance!

EDIT: I forgot to mention that I actually dual boot Ubuntu alongside with Windows 10 and it's all fine on Windows, so it shouldnt be a hardware issue.

Attaching output that @byte_commander requested, although I'm not sure which parts might be relevant, so feel free to ask for something else.

-- Logs begin at Sat 2019-01-19 23:10:53 CET, end at Mon 2019-01-21 17:02:14 CET. --
sty 19 23:11:10 Jakub systemd[1]: Starting Network Manager...
-- Subject: Unit NetworkManager.service has begun start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has begun starting up.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.0965] NetworkManager (version 1.10.6) is starting... (for the first time)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.0965] Read config: /etc/NetworkManager/NetworkManager.conf (lib: 10-dns-resolved.conf, 20-connectivity-ubuntu.conf, no-mac-addr-change.conf) (run: 10-globally-managed-devices.conf) (etc: default-wifi-powersave-on.conf)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.1478] manager[0x55c40b915060]: monitoring kernel firmware directory '/lib/firmware'.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.1478] monitoring ifupdown state file '/run/network/ifstate'.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.2971] hostname: hostname: using hostnamed
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.2971] hostname: hostname changed from (none) to "Jakub"
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.2975] dns-mgr[0x55c40b934150]: init: dns=systemd-resolved, rc-manager=symlink, plugin=systemd-resolved
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.2980] manager[0x55c40b915060]: rfkill: WiFi hardware radio set enabled
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.2981] manager[0x55c40b915060]: rfkill: WWAN hardware radio set enabled
sty 19 23:11:15 Jakub systemd[1]: Started Network Manager.
-- Subject: Unit NetworkManager.service has finished start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has finished starting up.
-- 
-- The start-up result is RESULT.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6914] init!
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6916]       interface-parser: parsing file /etc/network/interfaces
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6916]       interface-parser: finished parsing file /etc/network/interfaces
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6916] management mode: unmanaged
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6920] devices added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6920] device added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0): no ifupdown configuration found.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6921] devices added (path: /sys/devices/virtual/net/lo, iface: lo)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6921] device added (path: /sys/devices/virtual/net/lo, iface: lo): no ifupdown configuration found.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6921] end _init.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6921] settings: loaded plugin ifupdown: (C) 2008 Canonical Ltd.  To report bugs please use the NetworkManager mailing list. (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-settings-plugin-ifupdown.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6922] settings: loaded plugin keyfile: (c) 2007 - 2016 Red Hat, Inc.  To report bugs please use the NetworkManager mailing list.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6922] (194319552) ... get_connections.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6922] (194319552) ... get_connections (managed=false): return empty list.
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6924] get unmanaged devices count: 0
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6924] manager: rfkill: WiFi enabled by radio killswitch; enabled by state file
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6925] manager: rfkill: WWAN enabled by radio killswitch; enabled by state file
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6925] manager: Networking is enabled by state file
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.6926] dhcp-init: Using DHCP client 'dhclient'
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7064] Loaded device plugin: NMBondDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7064] Loaded device plugin: NMBridgeDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7065] Loaded device plugin: NMDummyDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7065] Loaded device plugin: NMEthernetDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7065] Loaded device plugin: NMInfinibandDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7066] Loaded device plugin: NMIPTunnelDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7066] Loaded device plugin: NMMacsecDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7066] Loaded device plugin: NMMacvlanDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7067] Loaded device plugin: NMPppDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7067] Loaded device plugin: NMTunDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7067] Loaded device plugin: NMVethDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7068] Loaded device plugin: NMVlanDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7068] Loaded device plugin: NMVxlanDeviceFactory (internal)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.7280] Loaded device plugin: NMWwanFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wwan.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8426] Loaded device plugin: NMBluezManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-bluetooth.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8548] Loaded device plugin: NMAtmManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-adsl.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8764] Loaded device plugin: NMTeamFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-team.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8783] Loaded device plugin: NMWifiFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wifi.so)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8805] device (lo): carrier: link connected
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8818] manager: (lo): new Generic device (/org/freedesktop/NetworkManager/Devices/1)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8842] manager: (enp2s0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/2)
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8870] keyfile: add connection in-memory (26a2fcfc-2f88-3ac6-bbfa-922e41b3c824,"Wired connection 1")
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8879] settings: (enp2s0): created default wired connection 'Wired connection 1'
sty 19 23:11:15 Jakub NetworkManager[675]: <info>  [1547935875.8899] device (enp2s0): state change: unmanaged -> unavailable (reason 'managed', sys-iface-state: 'external')
sty 19 23:11:16 Jakub NetworkManager[675]: <info>  [1547935876.0237] modem-manager: ModemManager available
sty 19 23:11:21 Jakub NetworkManager[675]: <info>  [1547935881.9903] manager: startup complete
sty 19 23:17:39 Jakub NetworkManager[675]: <info>  [1547936259.5727] modem-manager: ModemManager no longer available
sty 19 23:17:40 Jakub systemd[1]: Stopping Network Manager...
-- Subject: Unit NetworkManager.service has begun shutting down
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has begun shutting down.
sty 19 23:17:40 Jakub NetworkManager[675]: <info>  [1547936260.9605] caught SIGTERM, shutting down normally.
sty 19 23:17:41 Jakub NetworkManager[675]: <info>  [1547936261.0347] exiting (success)
sty 19 23:17:41 Jakub systemd[1]: Stopped Network Manager.
-- Subject: Unit NetworkManager.service has finished shutting down
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has finished shutting down.
-- Reboot --
sty 19 23:31:28 Jakub systemd[1]: Starting Network Manager...
-- Subject: Unit NetworkManager.service has begun start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has begun starting up.
sty 19 23:31:34 Jakub NetworkManager[655]: <info>  [1547937094.3010] NetworkManager (version 1.10.6) is starting... (for the first time)
sty 19 23:31:34 Jakub NetworkManager[655]: <info>  [1547937094.3011] Read config: /etc/NetworkManager/NetworkManager.conf (lib: 10-dns-resolved.conf, 20-connectivity-ubuntu.conf, no-mac-addr-change.conf) (run: 10-globally-managed-devices.conf) (etc: default-wifi-powersave-on.conf)
sty 19 23:31:34 Jakub NetworkManager[655]: <info>  [1547937094.3394] manager[0x55e8a8134060]: monitoring kernel firmware directory '/lib/firmware'.
sty 19 23:31:34 Jakub NetworkManager[655]: <info>  [1547937094.3394] monitoring ifupdown state file '/run/network/ifstate'.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.0905] hostname: hostname: using hostnamed
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.0905] hostname: hostname changed from (none) to "Jakub"
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.0909] dns-mgr[0x55e8a814e140]: init: dns=systemd-resolved, rc-manager=symlink, plugin=systemd-resolved
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.0914] manager[0x55e8a8134060]: rfkill: WiFi hardware radio set enabled
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.0914] manager[0x55e8a8134060]: rfkill: WWAN hardware radio set enabled
sty 19 23:31:35 Jakub systemd[1]: Started Network Manager.
-- Subject: Unit NetworkManager.service has finished start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has finished starting up.
-- 
-- The start-up result is RESULT.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8124] init!
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8126]       interface-parser: parsing file /etc/network/interfaces
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8126]       interface-parser: finished parsing file /etc/network/interfaces
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8127] management mode: unmanaged
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8132] devices added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8132] device added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0): no ifupdown configuration found.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8133] devices added (path: /sys/devices/virtual/net/lo, iface: lo)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8133] device added (path: /sys/devices/virtual/net/lo, iface: lo): no ifupdown configuration found.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8133] end _init.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8133] settings: loaded plugin ifupdown: (C) 2008 Canonical Ltd.  To report bugs please use the NetworkManager mailing list. (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-settings-plugin-ifupdown.so)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8134] settings: loaded plugin keyfile: (c) 2007 - 2016 Red Hat, Inc.  To report bugs please use the NetworkManager mailing list.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8134] (-1474907968) ... get_connections.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8134] (-1474907968) ... get_connections (managed=false): return empty list.
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8409] get unmanaged devices count: 0
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8410] manager: rfkill: WiFi enabled by radio killswitch; enabled by state file
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8410] manager: rfkill: WWAN enabled by radio killswitch; enabled by state file
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8410] manager: Networking is enabled by state file
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8412] dhcp-init: Using DHCP client 'dhclient'
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8826] Loaded device plugin: NMBondDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8827] Loaded device plugin: NMBridgeDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8827] Loaded device plugin: NMDummyDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8827] Loaded device plugin: NMEthernetDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8827] Loaded device plugin: NMInfinibandDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8827] Loaded device plugin: NMIPTunnelDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMMacsecDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMMacvlanDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMPppDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMTunDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMVethDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMVlanDeviceFactory (internal)
sty 19 23:31:35 Jakub NetworkManager[655]: <info>  [1547937095.8828] Loaded device plugin: NMVxlanDeviceFactory (internal)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.0364] Loaded device plugin: NMWwanFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wwan.so)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.2429] Loaded device plugin: NMBluezManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-bluetooth.so)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.2541] Loaded device plugin: NMAtmManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-adsl.so)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.4293] Loaded device plugin: NMTeamFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-team.so)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5365] Loaded device plugin: NMWifiFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wifi.so)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5830] device (lo): carrier: link connected
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5837] manager: (lo): new Generic device (/org/freedesktop/NetworkManager/Devices/1)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5850] manager: (enp2s0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/2)
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5864] keyfile: add connection in-memory (26a2fcfc-2f88-3ac6-bbfa-922e41b3c824,"Wired connection 1")
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5869] settings: (enp2s0): created default wired connection 'Wired connection 1'
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.5877] device (enp2s0): state change: unmanaged -> unavailable (reason 'managed', sys-iface-state: 'external')
sty 19 23:31:36 Jakub NetworkManager[655]: <info>  [1547937096.8349] modem-manager: ModemManager available
sty 19 23:31:42 Jakub NetworkManager[655]: <info>  [1547937102.7540] manager: startup complete
sty 19 23:31:55 Jakub NetworkManager[655]: <info>  [1547937115.8170] device changed (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0)
sty 19 23:31:55 Jakub NetworkManager[655]: <info>  [1547937115.9427] device changed (path: /sys/devices/virtual/net/lo, iface: lo)
sty 19 23:40:03 Jakub NetworkManager[655]: <info>  [1547937603.5046] modem-manager: ModemManager no longer available
sty 19 23:40:05 Jakub systemd[1]: Stopping Network Manager...
-- Subject: Unit NetworkManager.service has begun shutting down
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has begun shutting down.
sty 19 23:40:05 Jakub NetworkManager[655]: <info>  [1547937605.2318] caught SIGTERM, shutting down normally.
sty 19 23:40:05 Jakub NetworkManager[655]: <info>  [1547937605.2334] exiting (success)
sty 19 23:40:05 Jakub systemd[1]: Stopped Network Manager.
-- Subject: Unit NetworkManager.service has finished shutting down
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has finished shutting down.
-- Reboot --
sty 20 00:05:01 Jakub systemd[1]: Starting Network Manager...
-- Subject: Unit NetworkManager.service has begun start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has begun starting up.
sty 20 00:05:05 Jakub NetworkManager[665]: <info>  [1547939105.9198] NetworkManager (version 1.10.6) is starting... (for the first time)
sty 20 00:05:05 Jakub NetworkManager[665]: <info>  [1547939105.9200] Read config: /etc/NetworkManager/NetworkManager.conf (lib: 10-dns-resolved.conf, 20-connectivity-ubuntu.conf, no-mac-addr-change.conf) (run: 10-globally-managed-devices.conf) (etc: default-wifi-powersave-on.conf)
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.0296] manager[0x55e4df544060]: monitoring kernel firmware directory '/lib/firmware'.
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.0297] monitoring ifupdown state file '/run/network/ifstate'.
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.2266] hostname: hostname: using hostnamed
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.2266] hostname: hostname changed from (none) to "Jakub"
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.2271] dns-mgr[0x55e4df562140]: init: dns=systemd-resolved, rc-manager=symlink, plugin=systemd-resolved
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.2278] manager[0x55e4df544060]: rfkill: WiFi hardware radio set enabled
sty 20 00:05:06 Jakub NetworkManager[665]: <info>  [1547939106.2278] manager[0x55e4df544060]: rfkill: WWAN hardware radio set enabled
sty 20 00:05:06 Jakub systemd[1]: Started Network Manager.
-- Subject: Unit NetworkManager.service has finished start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit NetworkManager.service has finished starting up.
-- 
-- The start-up result is RESULT.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0366] init!
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0368]       interface-parser: parsing file /etc/network/interfaces
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0368]       interface-parser: finished parsing file /etc/network/interfaces
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0368] management mode: unmanaged
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0375] devices added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0375] device added (path: /sys/devices/pci0000:00/0000:00:1c.2/0000:02:00.0/net/enp2s0, iface: enp2s0): no ifupdown configuration found.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0376] devices added (path: /sys/devices/virtual/net/lo, iface: lo)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0376] device added (path: /sys/devices/virtual/net/lo, iface: lo): no ifupdown configuration found.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0376] end _init.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0377] settings: loaded plugin ifupdown: (C) 2008 Canonical Ltd.  To report bugs please use the NetworkManager mailing list. (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-settings-plugin-ifupdown.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0377] settings: loaded plugin keyfile: (c) 2007 - 2016 Red Hat, Inc.  To report bugs please use the NetworkManager mailing list.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0377] (-547882816) ... get_connections.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0378] (-547882816) ... get_connections (managed=false): return empty list.
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0381] get unmanaged devices count: 0
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0381] manager: rfkill: WiFi enabled by radio killswitch; enabled by state file
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0382] manager: rfkill: WWAN enabled by radio killswitch; enabled by state file
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0382] manager: Networking is enabled by state file
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0384] dhcp-init: Using DHCP client 'dhclient'
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0514] Loaded device plugin: NMBondDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0515] Loaded device plugin: NMBridgeDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0515] Loaded device plugin: NMDummyDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0515] Loaded device plugin: NMEthernetDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0516] Loaded device plugin: NMInfinibandDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0516] Loaded device plugin: NMIPTunnelDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0516] Loaded device plugin: NMMacsecDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0517] Loaded device plugin: NMMacvlanDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0517] Loaded device plugin: NMPppDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0518] Loaded device plugin: NMTunDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0518] Loaded device plugin: NMVethDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0518] Loaded device plugin: NMVlanDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0519] Loaded device plugin: NMVxlanDeviceFactory (internal)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0540] Loaded device plugin: NMWwanFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wwan.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0766] Loaded device plugin: NMBluezManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-bluetooth.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.0775] Loaded device plugin: NMAtmManager (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-adsl.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.1103] Loaded device plugin: NMTeamFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-team.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3617] Loaded device plugin: NMWifiFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-device-plugin-wifi.so)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3959] device (lo): carrier: link connected
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3967] manager: (lo): new Generic device (/org/freedesktop/NetworkManager/Devices/1)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3981] manager: (enp2s0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/2)
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3994] keyfile: add connection in-memory (26a2fcfc-2f88-3ac6-bbfa-922e41b3c824,"Wired connection 1")
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.3998] settings: (enp2s0): created default wired connection 'Wired connection 1'
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.4008] device (enp2s0): state change: unmanaged -> unavailable (reason 'managed', sys-iface-state: 'external')
sty 20 00:05:07 Jakub NetworkManager[665]: <info>  [1547939107.6129] modem-manager: ModemManager available
sty 20 00:05:13 Jakub NetworkManager[665]: <info>  [1547939113.5580] manager: startup complete
sty 20 00:12:02 Jakub NetworkManager[665]: <info>  [1547939522.9334] manager: sleep: sleep requested (sleeping: no  enabled: yes)
sty 20 00:12:02 Jakub NetworkManager[665]: <info>  [1547939522.9336] device (enp2s0): state change: unavailable -> unmanaged (reason 'sleeping', sys-iface-state: 'managed')
sty 20 00:12:02 Jakub NetworkManager[665]: <info>  [1547939522.9549] manager: NetworkManager state is now ASLEEP
sty 20 00:12:09 Jakub NetworkManager[665]: <info>  [1547939529.2651] manager: sleep: wake requested (sleeping: yes  enabled: yes)
sty 20 00:12:09 Jakub NetworkManager[665]: <info>  [1547939529.2653] device (enp2s0): state change: unmanaged -> unavailable (reason 'managed', sys-iface-state: 'managed')
sty 20 00:12:09 Jakub NetworkManager[665]: <info>  [1547939529.2809] manager: NetworkManager state is now DISCONNECTED
sty 20 00:23:21 Jakub systemd[1]: Stopping Network Manager...

Answer 1

Since you did a clean install recently, I'm betting the problem is actually hardware, not properly setup to be used with Ubuntu. I'd do lspci. From there, I would try to detect my network adapter (ethernet/wifi), find it's model and try to install the appropriate firmware package for the adapter to work.

I've had previous experience with a Broadcom BCM43XX network adapter that wasn't configured properly and as a result, WiFi couldn't find a network adapter to use. I used my phone as a USB router, downloaded the package "firmware-B43-installer", installed it, rebooted and it was all fixed.

Hope this helped.

Source: Installing Broadcom Wireless Drivers