The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
Yes, they are on a separate network drive at Getzner and everytime it loses connection (which happens a lot), our server cannot remount it for some reason.
They are a separate issue. Same with mods.
https://github.com/FAForever/downlords-faf-client/issues/3120
https://github.com/FAForever/downlords-faf-client/issues/3118