First of all, ask your parents or anyone in charge if your computer has a VPN installed or the connection is being hidden by a proxy, in that case, I'm afraid you will need to disable in order to be able to log-in to the server. Nevertheless, if you still don't have idea if you have a VPN/proxy or not, you can always go to
http://www.whatsmyip.org/ and
PM me your IP address (the one that doesn't let you to connect to the server) and I can check for you