The game server isn't letting you connect because the UID check is failing.
Please check that "C:\Program Files (x86)\Forged Alliance Forever\faf-uid.exe" exists and isn't blocked by antivirus or firewall.
If that doesn't help, please do the following:
1. Uninstall FAF
2. Delete C:\ProgramData\FAForever
3. Download and install this special debug build:
https://ci.appveyor.com/api/buildjobs/w ... -win32.msi4. Run that debug build and report results / upload forever.log