"our server performs every night at 4 o'clock a restart, only then the teams are always gone and must be recreated. Does anyone also have this problem, or maybe even a solution? We have also already contacted the developer directly, only he has referred to this community!"
First off, what developer? So, I have some things that should stay in the Server Config file but doesn't. Examples, is Hackable Crates (300 seconds, instead of 900) or Load orders on a plugin that's giving me an issue. Also, after restart, sometimes my Oil Rigs don't populate or my doors are open. So, I run scripts through the server to take care of things like this. If you're not familar with scheduled scripts, there is a plugin on UMod that works well too. It's called Auto Command. Pretty intuitive.
It doesn't do all the things I needed to do, so now I use the scripts through the scheduled tasks on my server, but I remember it working in a snap when I needed it too. Hope this helps.
https://umod.org/plugins/auto-commands