1

I just updated my laptop from 17.10 to 18.04 LTS. However, only my wifi connection still works, while the lan connection is not able to work anymore. I saw that others ran into similar issues after updating their system, however, nothing worked for me. Maybe someone has an idea. ifconfig gives me this output:

~$ ifconfig 
   enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    ether 54:e1:ad:bb:4d:5f  txqueuelen 1000  (Ethernet)
    RX packets 32507  bytes 5736300 (5.7 MB)
    RX errors 0  dropped 327  overruns 0  frame 0
    TX packets 1687  bytes 1327985 (1.3 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    device interrupt 16  memory 0xf1300000-f1320000  

   lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1000  (Lokale Schleife)
    RX packets 2599  bytes 221934 (221.9 KB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 2599  bytes 221934 (221.9 KB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

   wlp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 134.93.216.46  netmask 255.255.240.0  broadcast 134.93.223.255
    inet6 fe80::3e0f:9ef1:2208:6a3e  prefixlen 64  scopeid 0x20<link>
    inet6 2001:4c80:40:539:4dc9:e32f:747b:7f6a  prefixlen 64  scopeid 0x0<global>
    inet6 2001:4c80:40:539:f6b2:e234:8e22:6e62  prefixlen 64  scopeid 0x0<global>
    ether 00:28:f8:55:06:b8  txqueuelen 1000  (Ethernet)
    RX packets 682246  bytes 1011624146 (1.0 GB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 111926  bytes 13380382 (13.3 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

My /etc/network/interfaces looks like this:

 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback

Any help is appreciated. Thanks, Daniel

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  • 1
    tried it, apparently it did not work.
    – Daniel
    May 4, 2018 at 11:21
  • Can you ping directly your interface after set a static ip on it ? (sudo ip a add 192.168.1.50/24 dev enp0s31f6)
    – Eraseth
    May 4, 2018 at 15:20
  • I had a similar problem. My WiFi Adapter worked but my Ethernet didn't. First I removed all VMnet's (VMware Workstation/Player, Oracle VirtualBox...). Secondary I spoofed my Ethernet Adapters MAC Address because my DHCP Server didn't gave me a IP-Address probably because of my dual boot with Microsoft Windows. How to SEE HERE.
    – Dani
    Feb 15, 2020 at 12:34

4 Answers 4

2

I start from the principle that your computer is connect to your home LAN network with an ISP Box. You don't have any IP address on your Ethernet interface but the interface link seems to be up.

  1. Please run the command sudo dhclient -v enp0s31f6 in a terminal (this command will try to get an IP address from a DHCP server: your box).

  2. Then check if you receive an IP address (command ip address or ifconfig). If you doesn't get an address, please copy & paste the output of the command dhclient.

  3. If you correctly get an IP, then test your internet connectivity:

    ping 8.8.8.8 -I enp0s31f6
    

    8.8.8.8 is the address of Google’s DNS.

  4. If your not able to ping this address, then check the routes with the command ip route. Ensure that the IP of your box is the default gateway of your computer.

    Please check the configuration of the network manager. Go to Parameters → Network → Default → click on the gearwheel → IPv4, select Automatic (DHCP) and apply the change.

    IPv4 network configuration dialogue

2
  • Could you mention why the command - "sudo dhclient -v enp0s31f6" works? (in my case the enp--- was slightly different naming wise) However I seemed to have the same issue, my link was up and working but internet wouldn't want to connect thru, then that command worked and my internet works.
    – Nick Bell
    Aug 30, 2018 at 15:58
  • Probably because the first try to obtain an IP through DHCP failed and then perform it manually solve the problem.
    – Eraseth
    Aug 31, 2018 at 7:07
1

I had similar issue upgrading from 16.04 to 18.04, in my situation wifi connection worked and LAN connection was dropping every 30/60 sec.

In ifconfig output there was a bridge connection with static ip as is as gateway ip!

When I deleted this bridge connection everything restored and LAN was OK.

0

/etc/network/interfaces hold a very little bit of the networking information since Ubuntu 18.04 LTS.

Configuration changed to somewhat more powerful /etc/netplan/*.yaml

For example, /etc/netplan/01-netcfg.yaml

It looks somewhat different by syntax:

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      addresses: [ 31.147.205.54/23 ]
      gateway4: 31.147.204.1
      nameservers:
          search: [ alu.hr ]
          addresses:
              - "161.53.2.69"
              - "161.53.2.70"
              - "161.53.235.3"

A broad set of configuration examples can be found here:

https://netplan.io/examples

-2

GIGABYTE AB350M-Gaming 3 rev. 1 F22 UBUNTU 18.04 LAN ISSUE

  1. IP link show (know your LAN hardware names).
  2. sudo nano /etc/network/interfaces and edit proper LAN name e. g. enp3so/enp5s0.
  3. Ctrl+O (save), then Ctrl+X (exit).
  4. Restart server.
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  • 1
    What exactly do you recommend to edit in /etc/network/interfaces and why is that better than to reconfigure Network Manager (e. g. like in the accepted answer)? Sep 17, 2018 at 8:10
  • to better understand ubuntu .. :) Oct 5, 2018 at 1:44

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