systemd 249.11-0ubuntu3.11 does *not* solve the issue for me. I seem to be running into the same situation as Werner in #32 where `optional: true` from the netplan config is not being respected. 

systemd-networkd-wait-online seems to ignore `RequiredForOnline=no` in the .network config.

Netplan config:

ubuntu@ubuntu:~$ sudo netplan get
network:
  version: 2
  ethernets:
    eth0:
      optional: true
      dhcp4: true
      dhcp6: true
    pfe:
      match:
        name: "pfe*"
      optional: true
      dhcp4: true
      dhcp6: true

systemd-networkd configs:

ubuntu@ubuntu:~$ grep '' /run/systemd/network/10-netplan-*
/run/systemd/network/10-netplan-eth0.network:[Match]
/run/systemd/network/10-netplan-eth0.network:Name=eth0
/run/systemd/network/10-netplan-eth0.network:
/run/systemd/network/10-netplan-eth0.network:[Link]
/run/systemd/network/10-netplan-eth0.network:RequiredForOnline=no
/run/systemd/network/10-netplan-eth0.network:
/run/systemd/network/10-netplan-eth0.network:[Network]
/run/systemd/network/10-netplan-eth0.network:DHCP=yes
/run/systemd/network/10-netplan-eth0.network:LinkLocalAddressing=ipv6
/run/systemd/network/10-netplan-eth0.network:
/run/systemd/network/10-netplan-eth0.network:[DHCP]
/run/systemd/network/10-netplan-eth0.network:RouteMetric=100
/run/systemd/network/10-netplan-eth0.network:UseMTU=true
/run/systemd/network/10-netplan-pfe.network:[Match]
/run/systemd/network/10-netplan-pfe.network:Name=pfe*
/run/systemd/network/10-netplan-pfe.network:
/run/systemd/network/10-netplan-pfe.network:[Link]
/run/systemd/network/10-netplan-pfe.network:RequiredForOnline=no
/run/systemd/network/10-netplan-pfe.network:
/run/systemd/network/10-netplan-pfe.network:[Network]
/run/systemd/network/10-netplan-pfe.network:DHCP=yes
/run/systemd/network/10-netplan-pfe.network:LinkLocalAddressing=ipv6
/run/systemd/network/10-netplan-pfe.network:
/run/systemd/network/10-netplan-pfe.network:[DHCP]
/run/systemd/network/10-netplan-pfe.network:RouteMetric=100
/run/systemd/network/10-netplan-pfe.network:UseMTU=true

eth0 is configured:
ubuntu@ubuntu:~$ networkctl list
IDX LINK      TYPE     OPERATIONAL SETUP
  1 lo        loopback carrier     unmanaged
  2 eth0      ether    routable    configured
  3 can0      can      off         unmanaged
  4 can1      can      off         unmanaged
  5 llcecan0  can      off         unmanaged
  6 llcecan1  can      off         unmanaged
  7 llcecan2  can      off         unmanaged
  8 llcecan3  can      off         unmanaged
  9 llcecan4  can      off         unmanaged
 10 llcecan5  can      off         unmanaged
 11 llcecan6  can      off         unmanaged
 12 llcecan7  can      off         unmanaged
 13 llcecan8  can      off         unmanaged
 14 llcecan9  can      off         unmanaged
 15 llcecan10 can      off         unmanaged
 16 llcecan11 can      off         unmanaged
 17 llcecan13 can      off         unmanaged
 18 llcecan14 can      off         unmanaged
 19 llcecan15 can      off         unmanaged
 20 pfe0      ether    degraded    configuring
 21 pfe1      ether    no-carrier  configuring
 22 pfe2      ether    no-carrier  configuring

22 links listed.


systemd-networkd-wait-online times out:

ubuntu@ubuntu:~$ sudo SYSTEMD_LOG_LEVEL=debug /lib/systemd/systemd-networkd-wait-online --timeout=10
Found link 22
Found link 21
Found link 20
Found link 19
Found link 18
Found link 17
Found link 16
Found link 15
Found link 14
Found link 13
Found link 12
Found link 11
Found link 10
Found link 9
Found link 8
Found link 7
Found link 6
Found link 5
Found link 4
Found link 3
Found link 2
Found link 1
llcecan2: link is not managed by networkd (yet?).
llcecan0: link is not managed by networkd (yet?).
llcecan7: link is not managed by networkd (yet?).
llcecan9: link is not managed by networkd (yet?).
llcecan4: link is not managed by networkd (yet?).
llcecan10: link is not managed by networkd (yet?).
pfe1: link is ignored
can0: link is not managed by networkd (yet?).
pfe0: link is ignored
llcecan3: link is not managed by networkd (yet?).
eth0: link is ignored
llcecan11: link is not managed by networkd (yet?).
llcecan6: link is not managed by networkd (yet?).
lo: link is ignored
llcecan13: link is not managed by networkd (yet?).
llcecan1: link is not managed by networkd (yet?).
can1: link is not managed by networkd (yet?).
pfe2: link is ignored
llcecan14: link is not managed by networkd (yet?).
llcecan8: link is not managed by networkd (yet?).
llcecan15: link is not managed by networkd (yet?).
llcecan5: link is not managed by networkd (yet?).
Timeout occurred while waiting for network connectivity.