Firewall fails on reboot

Thanks, that seems to work fine, all firewall rules are there!
In the meantime, I created another container, using the snapshot lxc repo, which seems to be the new 22.03.0 branch. At least it uses nftables. I will do more tests, but the basic firewall rules seem to be there after boot. No nftables experience up to now.
Edit: FYI: a reboot of the 21.02.3 container via Luci does not reboot the container, it just terminates it.

Mhh are you sure? It seems to work fine for me when rebooting from LuCI:

ยป lxc-monitor -n openwrt2102 
'openwrt2102' exited with status [0]
'openwrt2102' changed state to [STOPPING]
'openwrt2102' changed state to [STOPPED]
'openwrt2102' changed state to [STARTING]
'openwrt2102' changed state to [RUNNING]

Maybe it tries but just fails to startup? Happened to me sometimes when stopping/restarting too soon due to some conflict on the virtual interfaces iirc...