I know it’s an old thread, but it was never solved and I had the same issue. Found this page and wanted to help anyone else who finds it.
I’ve just managed to get Debian 12 Bullseye working with the latest Cloud image on PiMox 7:
https://uk.lxd.images.canonical.com/images/debian/bookworm/arm64/cloud/20230614_05:24/rootfs.tar.xz
When configuring the CT, leave IP = Static. Do not enter any IP address.
Boot the CT, enter the CTs console.
Install Nano (who doesn’t need nano anyway! You can use vi/vim if you’re fancy, I’m not)
apt install nano
Edit the network configuration file
nano /etc/systemd/network/eth0.network
Change:
[Network]
DHCP=yes
to
[Network]
Address=192.168.1.101/24
Gateway=192.168.1.1
Restart Systemd Networkd
systemctl restart systemd-networkd
Check the static IP is set (you’ll probably also see the DHCP IP is still there)
ip -c a
Reboot
reboot now
You’ve now got the static IP set up (if you don’t reboot, it’ll still keep the DHCP assigned IP in addition to the static)