@lothar863 Try adding an exception/exclusion for the FAF Client in both the active scan & firewall sections of your AV software & Windows Security. I would also try clearing the cache of each browser you've tried & then try again.
If you still have an issue, then click the Reply button at the bottom between the 👁 (View) icon & the "Mark unread" button. Next, open Run (Windows+R) & go to the following:
%USERPROFILE%/AppData\Roaming\Forged Alliance Forever\logs
Sort by Date Modified. From there, drag/drop your client.log file (the Text Document file without the date) into the Reply message window so those that can help (not me) have that data to look at.