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!
I've locked this topic. From now on if you have such an issue please send me a forum PM with the accounts involved so that I may help you out. @KamauWarrior1 included
@sheikah
I have no active antivirus and have already manually allowed FAF client thru firewall with no effect.
Could there be some kind of a ban or error with my wifi IP adress on the server or something similar?
You just need to ignore and run anyway. It is a false positive from windows since we did not pay to register with them. If you got it from the website FAForever.com it is safe.