Netplan not connecting bridge with static IP

[Jane Atkinson]

System is Xubuntu 20.04, built up from Xubuntu-core base.

I have a very simple bridge consisting of one ethernet interface, which I need for bridging to QEMU/KVM vms. It used to work properly on 18.04.

The .yaml file is as follows:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0:
      dhcp4: no

  bridges:
    br0:
      dhcp4: no
      dhcp6: no
      addresses: [ 192.168.1.65/24 ]
      gateway4: 192.168.1.1
      nameservers:
        addresses: [ 192.168.1.1 ]
      interfaces:
        - enp3s0

On logging in immediately after bootup, I see that br0 is UP, but has no IP address assigned to it.

syslog contains the item:

systemd-networkd[367]: br0: Could not set route: Nexthop has invalid gateway. Network is unreachable

If I run "sudo netplan apply", either after logging in or as a @reboot cron job, the bridge then connects with no problem.

If I change br0 to dhcp4: yes (and remove addresses, gateway4 and nameservers), br0 connects automatically on bootup. I can tweak dnsmasq on the router so that the machine gets the IP I want every time, but I'd prefer to be able to set a static IP address and have it work.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: netplan.io 0.98-0ubuntu4
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu26
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sat Apr 11 22:44:49 2020
InstallationDate: Installed on 2020-04-08 (3 days ago)
InstallationMedia: Xubuntu Core 20.04 - amd64 - 20200403
SourcePackage: netplan.io
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Kees Bakker (keestux)]

Same situation for me. I installed Ubuntu 20.04 (beta) on a new
server and used the exact same netplan setup as on an Ubuntu 18.04 server.

At startup it hangs for a long time at "Wait for Network to be Configured"
which never succeeds. Eventually I can login, but the network did not
get up.

This is quite annoying since it is now impossible to remotely reboot.
Well, I can reboot, but then the system remains offline. :-(

Indeed "systemctl restart systemd-networkd" completes without error, and
the bridge is up.

To me it is not clear whether this is a bug in netplan or in systemd-networkd or in the combination of the two.

[Kees Bakker (keestux)]

A bit of logging from journalctl

Apr 22 11:06:21 ijssel systemd[1]: Starting Network Service...
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: netdev ready
Apr 22 11:06:22 ijssel systemd-networkd[1006]: Enumeration completed
Apr 22 11:06:22 ijssel systemd[1]: Started Network Service.
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: IPv6 successfully enabled
Apr 22 11:06:22 ijssel systemd-networkd[1006]: eno2: IPv6 successfully enabled
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: Link UP
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: Gained carrier
Apr 22 11:06:22 ijssel systemd-networkd[1006]: eno2: Link UP
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: Lost carrier
Apr 22 11:06:22 ijssel systemd-networkd[1006]: eno1: Link UP
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: Could not set route: Nexthop has invalid gateway. Network is unreachable
Apr 22 11:06:22 ijssel systemd-networkd[1006]: br0: Failed
Apr 22 11:06:25 ijssel systemd-networkd[1006]: eno2: Gained carrier
Apr 22 11:06:26 ijssel systemd-networkd[1006]: eno1: Gained carrier
Apr 22 11:06:26 ijssel systemd-networkd[1006]: br0: Gained carrier
Apr 22 11:06:27 ijssel systemd-networkd[1006]: eno2: DHCPv4 address 172.16.16.120/22 via 172.16.16.1
Apr 22 11:06:27 ijssel systemd-networkd[1006]: eno2: Gained IPv6LL

Now compare that with the same (working) setup on Ubuntu 18.04

mrt 20 17:44:02 maas systemd[1]: Starting Network Service...
mrt 20 17:44:02 maas systemd-networkd[983]: br0: netdev ready
mrt 20 17:44:02 maas systemd-networkd[983]: Enumeration completed
mrt 20 17:44:02 maas systemd[1]: Started Network Service.
mrt 20 17:44:02 maas systemd-networkd[983]: lo: Link is not managed by us
mrt 20 17:44:02 maas systemd-networkd[983]: eno2: Link is not managed by us
mrt 20 17:44:02 maas systemd-networkd[983]: eno1: Link is not managed by us
mrt 20 17:44:06 maas systemd-networkd[983]: eno1: Gained carrier
mrt 20 17:44:06 maas systemd-networkd[983]: eno1: Configured
mrt 20 17:44:06 maas systemd-networkd[983]: br0: Gained carrier
mrt 20 17:44:07 maas systemd-networkd[983]: eno1: Gained IPv6LL
mrt 20 17:44:08 maas systemd-networkd[983]: br0: Gained IPv6LL
mrt 20 17:44:08 maas systemd-networkd[983]: br0: Configured

[Kees Bakker (keestux)]

This may be the same bug as https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1860926

[Dan Streetman (ddstreet)]

Yes, it certainly seems like it's the same problem; I'm going to mark this as a dup of that bug.

[Sylvain Le Blanc (naz9ul)]

Hi, please make shure that we are not running in circle with both bug mark as duplicate has each other...