Comment 1 for bug 2012546

Hello there,

Netplan doesn't support configuring zones in network manager keyfiles yet. Although you can do that with the "passthrough" property. Example:

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    enp2s0:
      dhcp4: true
      networkmanager:
        passthrough:
          connection.zone: internal

After applying your configuration (or rebooting) you will find the lines below in /var/run/NetworkManager/system-connections/netplan-enp2s0.nmconnection:

#Netplan: passthrough setting
zone=internal

I hope it helps :)