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!
Which security software?
Do you have the latest W10 updates?
Which language is default for your OS?
Does your windows' username, or does any path to FAF/SC contain Cyrillic chars?
Edit: I believe I see the "Avast" icon - if you use that security, try uninstalling it and try again.
