Around midnight I decided to upgrade my home router to Debian 12. After one hour of troubleshooting manually I managed to save a few seconds by not reading the fine documentation, felt great!

First of all, I’m using systemd-resolved (and systemd-networkd) to do DNS on my router. That had been split into a separate package, but easy to install manually:

apt install systemd-resolved

After reboot I noticed that I couldn’t reach my firewall anymore. 😢

Brought forth my serial to USB converter, connected to the machine and…all interfaces were fine, except for my LACP bond which was down. All my VLANs goes over that bond, so not great. But after manually bringing the interface up everything worked again. Interesting.

I saved a few more seconds of trying to understand why and just solved it with a oneshot systemd service:

[Unit]
Description=Run a bond1 link up due to reasons
Wants=network-online.target
After=network.target network-online.target

[Service]
Type=oneshot
RemainAfterExit=1
ExecStart=/usr/sbin/ip link set bond1 up

[Install]
WantedBy=multi-user.target

Saved the file as /etc/systemd/system/bond-link-up.service, enabled it and rebooted.