Can only login once with an account

Hello!
Yesterday, I joined this server and everything worked great in the beginning. However, after the first logout, I couldn't log back in - most of the time I got an "unable to connect", sometimes a "this account is no longer in use". I tried everything from deleting WTF, reinstalling the client and using a VPN.
Today I created a new account to test wether that would work, and indeed it did. However, it faced the same problem - logged out and cannot log back in again.
Login on the site works no problem. It leads me to believe that this is a serverside issue.
Got an idea what this might be?
Greetings, MonkeyKhan
Yesterday, I joined this server and everything worked great in the beginning. However, after the first logout, I couldn't log back in - most of the time I got an "unable to connect", sometimes a "this account is no longer in use". I tried everything from deleting WTF, reinstalling the client and using a VPN.
Today I created a new account to test wether that would work, and indeed it did. However, it faced the same problem - logged out and cannot log back in again.
Login on the site works no problem. It leads me to believe that this is a serverside issue.
Got an idea what this might be?
Greetings, MonkeyKhan