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!
@boaty-mcboatface You should not have to do it every game. The fact that you do tells me that there's a file permissions issue causing the game to not be able to save changes to the game.prefs file.
Have you at any time run the FAF Client or any version of SCFA as Admin?