I have a client ubuntu 18.04 PC which is connected to the internet but DNS is not working. At first I thought I would have to configure the netplan yaml file which I did like:

network:

  version: 2

  renderer: NetworkManager

  ethernets:

    enp2s0:

      dhcp4: no

      addresses: [10.246.5.248/24]

      gateway4: 10.246.5.254

      nameservers:

        addresses: [10.246.5.1, 127.0.0.53]

        search: [<my_domain_name>]

sudo netplan --debug apply returned no errors and I restarted network-manager, but the network configuration doesn't change no matter how I edit the yaml file.

Then, following the answer to this question, I removed the ethernets configuration from the yaml file, edited my /etc/network/interfaces and restarted the network-manager, but again no changes in the IP address and name servers are being made.

Then, I've tried to run nm-connection-editor. No interfaces where being listed there, so I've tried adding one interface with my configurations. Again no changes in network configuration, even after restarting the network-manager.

My /etc/resolv.conf file has a symlink to /run/systemd/resolve/stub-resolv.conf. If I edit the stub with my DNS configuration, the DNS starts working, but only until I reboot.

Did I miss something? My guess is that there's other service/program that is changing the resolv.conf. How do I determine which is and configure my DNS there?