Wifi has stopped working unexpectedly on Ubuntu 18.04.1 LTS

Question

I can connect to the network, but I can't access the internet.

I have tried several solutions, such as:

• Update the Kernel to the last one version.
• Set up a list of DNSs (como 8.8.8.8) in the wifi settings.
• Set up the property wifi.scan-rand-mac-address to no (Actually, I was already working this way).

When I use a Live CD I get access. It stopped working after a while. As I did not use the wifi much regularly, I can't tell when it stopped working.

In the browser, I get DNS_PROB_START and then DNS_PROBE_FINISHED_NO_INTERNET.

$ sudo lshw -class network

      descrição: Interface sem fio
       produto: QCA9377 802.11ac Wireless Network Adapter
       fabricante: Qualcomm Atheros
       ID físico: 0
       informações do barramento: pci@0000:02:00.0
       nome lógico: wlp2s0
       versão: 31
       serial: 5c:c9:d3:8c:87:ff
       largura: 64 bits
       clock: 33MHz
       capacidades: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuração: broadcast=yes driver=ath10k_pci driverversion=4.18.0-041800-generic firmware=WLAN.TF.1.0-00002-QCATFSWPZ-5 ip=10.116.199.144 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       recursos: irq:129 memória:a1000000-a11fffff

$ lspci

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 02)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Device 9d4e (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
02:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)

$ cat /etc/issue.net; uname -ar

Ubuntu 18.04.1 LTS
Linux magneto 4.18.0-041800-generic #201808122131 SMP Sun Aug 12 21:33:20 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

$ rfkill list all

0: ideapad_wlan: Wireless LAN
    Soft blocked: no
    Hard blocked: no
1: ideapad_bluetooth: Bluetooth
    Soft blocked: yes
    Hard blocked: no
2: hci0: Bluetooth
    Soft blocked: yes
    Hard blocked: no
3: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no

$ dmesg

[ 6062.371799] wlp2s0: disconnect from AP 0e:8d:cb:6f:63:bc for new auth to 0e:8d:cb:6f:71:01
[ 6062.378165] wlp2s0: authenticate with 0e:8d:cb:6f:71:01
[ 6062.413159] wlp2s0: send auth to 0e:8d:cb:6f:71:01 (try 1/3)
[ 6062.413950] wlp2s0: authenticated
[ 6062.421667] wlp2s0: associate with 0e:8d:cb:6f:71:01 (try 1/3)
[ 6062.423506] wlp2s0: RX ReassocResp from 0e:8d:cb:6f:71:01 (capab=0x1011 status=0 aid=6)
[ 6062.427281] wlp2s0: associated
[ 6062.427355] wlp2s0: Limiting TX power to 30 (30 - 0) dBm as advertised by 0e:8d:cb:6f:71:01
[ 6062.427564] ath: EEPROM regdomain: 0x804c
[ 6062.427566] ath: EEPROM indicates we should expect a country code
[ 6062.427567] ath: doing EEPROM country->regdmn map search
[ 6062.427568] ath: country maps to regdmn code: 0x3b
[ 6062.427570] ath: Country alpha2 being used: BR
[ 6062.427571] ath: Regpair used: 0x3b
[ 6062.427573] ath: regdomain 0x804c dynamically updated by country element
[ 6941.786152] perf: interrupt took too long (3152 > 3130), lowering kernel.perf_event_max_sample_rate to 63250

$ ls -al /etc/resolv.conf

lrwxrwxrwx 1 root root 24 jul 26 14:09 /etc/resolv.conf -> /run/connman/resolv.conf

$ ping -c3 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.

--- 8.8.8.8 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 1999ms

$ cat /etc/resolv.conf

# Generated by Connection Manager
nameserver ::1
nameserver 127.0.0.1

$ systemctl list-unit-files output here

$ route

Tabela de Roteamento IP do Kernel
Destino         Roteador        MáscaraGen.    Opções Métrica Ref   Uso Iface
default         _gateway        0.0.0.0         UG    100    0        0 enp1s0
10.116.199.0    0.0.0.0         255.255.255.0   U     100    0        0 enp1s0

Thanks for listening