today i added the server to gtracker,worked for awhile and now it says that : THIS SERVER CANNOT BE SCANNED,the server its on,no port closed,i did not make any change to server,just worked for a few hours then boom...the server ip
93.119.24.51:27015.

PS. This happens when i change server hostname to GameTrackerClaimServer,when i put back mix.indungi.ro its working,so what can i do? cause i wanna claim the server and i cant

There should be no problem if it's just a name change. If you're changing the name via restarting the server, make sure you wait for it to come back online before you hit the Claim Ownership button.

same problem,when i change the name the site tels me that my server its down...but im on it and playing as usual,but when i put the original server name everything its ok...

Try contacting your host. I believe Krond blocks traffic when your server has the claim name because of security issues they had in the past.