In the Cockpit, you see an error message: ‘Cannot refresh cache whilst offline’ in the available updates section.

One solution is to create a fake Network Manager connection, and the other is to configure the network with a Network Manager backend. Next is the instruction for the second option.

Add ‘renderer: NetworkManager‘ line after the configuration version as follows:

sudo nano /etc/netplan/50-cloud-init.yaml

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    ens6f0:
      addresses:
      - "172.25.79.37/20"
      nameservers:
        addresses:
        - 172.25.64.11
        search:
        - atdomain.local
      routes:
      - to: "default"
        via: "172.25.64.1"

Save the configuration and restart the netplan with sudo systemctl restart netplan.service