@enr0n, yes, I did restart systemd-networkd after creating /etc/systemd/network/10-netplan-vlan1.network.d/keep_master.conf.
If you want to reproduce, the steps outlined in the bug descriptions should provide you with a simple reproducer. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/2036127 Title: Restarting `systemd-networkd` looses unmanaged bridged parents Status in systemd package in Ubuntu: Invalid Bug description: My home network comprises many VLANs managed by `systemd- networkd`/`netplan`. Those VLANs are then used as parent interfaces for LXD networks. Whenever `systemd-networkd` is restarted (i.e: post- update), my whole network breaks because all the unmanaged bridges lose their parent devices. Another way to see it is that `systemd- networkd` undoes the `master` setting of those VLAN devices. Here is a simplified reproducer: 1. Create a `vlan1` device $ lxc launch ubuntu:22.04 networkd-bug Creating networkd-bug Starting networkd-bug $ lxc file push - networkd-bug/etc/netplan/99-vlan1.yaml << EOF network: version: 2 vlans: vlan1: id: 1 link: eth0 EOF $ lxc exec networkd-bug -- netplan apply 2. Manually create a bridge and join `vlan1` to it $ lxc exec networkd-bug -- ip link add br0 type bridge $ lxc exec networkd-bug -- ip link set vlan1 master br0 $ lxc exec networkd-bug -- ip link 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: vlan1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP mode DEFAULT group default qlen 1000 link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff 3: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether 42:b6:31:01:47:9a brd ff:ff:ff:ff:ff:ff 164: eth0@if165: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff link-netnsid 0 3. Restart `systemd-networkd` $ lxc exec networkd-bug -- systemctl restart systemd-networkd 4. Notice `vlan1` lost it's master config $ lxc exec networkd-bug -- ip link 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: vlan1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff 3: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether 42:b6:31:01:47:9a brd ff:ff:ff:ff:ff:ff 164: eth0@if165: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff link-netnsid 0 Ideally, `vlan1` should retain it's `master` setting and I wouldn't loose connectivity :) Additional information: # apt-cache policy systemd netplan.io iproute2 systemd: Installed: 249.11-0ubuntu3.9 Candidate: 249.11-0ubuntu3.9 Version table: *** 249.11-0ubuntu3.9 500 500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages 100 /var/lib/dpkg/status 249.11-0ubuntu3.7 500 500 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages 249.11-0ubuntu3 500 500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages netplan.io: Installed: 0.105-0ubuntu2~22.04.3 Candidate: 0.105-0ubuntu2~22.04.3 Version table: *** 0.105-0ubuntu2~22.04.3 500 500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages 100 /var/lib/dpkg/status 0.104-0ubuntu2 500 500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages iproute2: Installed: 5.15.0-1ubuntu2 Candidate: 5.15.0-1ubuntu2 Version table: *** 5.15.0-1ubuntu2 500 500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages 100 /var/lib/dpkg/status # lsb_release -rd Description: Ubuntu 22.04.3 LTS Release: 22.04 # uname -a Linux networkd-bug 6.2.0-32-generic #32~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Aug 18 10:40:13 UTC 2 x86_64 x86_64 x86_64 GNU/Linux To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/2036127/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp