Comment 1 for bug 2008952

There are a couple of significant issues that may be leading to this symptom:

 1. On Desktop live server images, something is laying down a competing file for management of the wired NIC on my laptop:

/etc/netlan/01-network-manager-all.yaml
# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager

Yet /etc/cloud/cloud.cfg specifies priority order of network renderers to prefer using netplan insteaad of NetworkManager:
   networks:
       renderers: ['netplan', 'eni', 'sysconfig']
       activators: ['netplan', 'eni', 'network-manager', 'networkd']

This causes cloud-init to also write out /etc/netplan/50-cloud-init.yaml which also tries to claim management of enp0s31f6 under systemd-networkd:

network:
  version: 2
  ethernets:
    enp0s21f6:
      dhcp4: true
      match:
        macaddress: 6c:24:08:9e:54:e7
      set-name: enp0s31f6

The result is undetermined behavior in early boot as NetworkManager and systemd-networkd fight over who owns the wired device. This could be the resulting DNS lookup failures we are seeing.

Resolution: I think desktop images want to avoid telling cloud-init to render networking using netplan. I believe we are missing this proposed fix to livecd rootfs:

https://code.launchpad.net/~dbungert/livecd-rootfs/+git/livecd-rootfs/+merge/427445