I am kicked, why you do not answer to my forum post?

Currently we doing silent maintenance work on the backend and therefore you need to wait until such cases can be checked and cleared again. We will most likely notify all users that posted to the » kicked from server forums « with such an issue via » Private Message « as soon as the current maintenance is done. Due to multiple changes this maintenance takes longer than usual - please be patient, thanks.

Why do I get kicked from the server - is this a bug?

Either you changed your CD-key way to often and therefore your current key is not accepted anymore or you are in an untrusted network. Thus if you have changed your CD-key you may switch back to your previous CD-key you could play with or you need to wait until the case can be checked (read above).
In any case you should disable your VPN and try an » Unban Request « before you post to the forums!