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Fixing the network after upgrading to Ubuntu 18.04 LTS from 16.04 LTS

December 18th, 2018

Just updated 16.04LTS to 18.04LTS, went easier and smoother than expected.

Under the hood there are major changes in Ubuntu, I decided to stick to Unity rather then the new Gnome 3, it’s much smoother on older hardware. You only change the setting at login once and you done.

The only nasty thing: DNS (Pi-Hole) was not working. I could fix that by manually setting the DNS server in /etc/resolv.conf from `nameserver 127.0.0.53` to the DNS of my router, but that would not persist a restart.

To get info about your network and DNS:


systemd-resolve --status

Link 1 (eth0)
      Current Scopes: none
       LLMNR setting: yes
MulticastDNS setting: no

Current scopes is none, but it should be DNS

Seems there was something wrong with the NetworkManager. Somehow in the past I’ve manually edited `/etc/NetworkManager/NetworkManager.conf` file. Can’t remember when I did that, could be years ago, Ubuntu 10.04 or something ;).

I had to comment out the line that explicitly set `no-auto-default`, meaning don’t let the NetworkManager create a default wired connection for my ethernet card.  

[main]
...
#no-auto-default=<mac-adress>
...
[ifupdown]
managed=false

After commenting it out, NetworkManager could create a default connection and after restart (the daemon), everything was OK. DNS was working.

systemd-resolve --status
Link 1 (eth0)
Current Scopes: DNS
LLMNR setting: yes
MulticastDNS setting: no

As you can see DNS is now working

Maybe this can help you, if you experience the same troubles.

This entry was posted on Tuesday, December 18th, 2018 at 2:45 pm and is filed under Webtechnology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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