Constellation:

Proxmox 8.1.4

LXC (container) -> Debian 12.2->12.4

After installing Omada with standard Deb12 options, it has installed Java 17 in background. Omada is working very well at first look.

BUT I had to change hardware, made backup and tried to restore. It always brought failure.

I started to investigate, what the problem is, after some installations with focal ubuntu, deb11 and deb12 I found the solution: Java 11 (headless) does it!

So, if you need working backup with restore, you have to install Java 11!

Just for info.