Comment 19 for bug 1802004

I am also running into this problem on Ubuntu Core 20 using the following configuration:

network:
  version: 2
  renderer: networkd
  ethernets:
    en1:
      match:
        driver: "imx-dwmac"
      addresses:
      - "192.168.0.200/24"
      set-name: "en1"
    en2:
      match:
        driver: "fec"
      dhcp4: true
      dhcp6: true
      set-name: "en2"

This only affects networkd; with "renderer: NetworkManager" everything works correctly.

It seems like systemd-networkd doesn't recognise one of the interfaces:

iotuc@ubuntu:~$ sudo networkctl
IDX LINK TYPE OPERATIONAL SETUP
  1 lo loopback carrier unmanaged
  2 en2 ether routable configured
  3 en1 ether off unmanaged
  4 wlan0 wlan routable configured

4 links listed.

The "en2" interface works, so it seems like it's not reproducible for every configuration.

The files generated for systemd-networkd:

iotuc@ubuntu:~$ grep '' /run/systemd/network/10-netplan-en*
/run/systemd/network/10-netplan-en1.link:[Match]
/run/systemd/network/10-netplan-en1.link:Driver=imx-dwmac
/run/systemd/network/10-netplan-en1.link:
/run/systemd/network/10-netplan-en1.link:[Link]
/run/systemd/network/10-netplan-en1.link:Name=en1
/run/systemd/network/10-netplan-en1.link:WakeOnLan=off
/run/systemd/network/10-netplan-en1.network:[Match]
/run/systemd/network/10-netplan-en1.network:Driver=imx-dwmac
/run/systemd/network/10-netplan-en1.network:Name=en1
/run/systemd/network/10-netplan-en1.network:
/run/systemd/network/10-netplan-en1.network:[Network]
/run/systemd/network/10-netplan-en1.network:LinkLocalAddressing=ipv6
/run/systemd/network/10-netplan-en1.network:Address=192.168.0.200/24
/run/systemd/network/10-netplan-en2.link:[Match]
/run/systemd/network/10-netplan-en2.link:Driver=fec
/run/systemd/network/10-netplan-en2.link:
/run/systemd/network/10-netplan-en2.link:[Link]
/run/systemd/network/10-netplan-en2.link:Name=en2
/run/systemd/network/10-netplan-en2.link:WakeOnLan=off
/run/systemd/network/10-netplan-en2.network:[Match]
/run/systemd/network/10-netplan-en2.network:Driver=fec
/run/systemd/network/10-netplan-en2.network:Name=en2
/run/systemd/network/10-netplan-en2.network:
/run/systemd/network/10-netplan-en2.network:[Network]
/run/systemd/network/10-netplan-en2.network:DHCP=yes
/run/systemd/network/10-netplan-en2.network:LinkLocalAddressing=ipv6
/run/systemd/network/10-netplan-en2.network:
/run/systemd/network/10-netplan-en2.network:[DHCP]
/run/systemd/network/10-netplan-en2.network:RouteMetric=100
/run/systemd/network/10-netplan-en2.network:UseMTU=true