If you are getting instantly disconnected before you see the tower, then it could be a number of things.
1) Run PingPlotter to the server and see if there is an issue between your computer and the server.
2) Make sure you do not have AVG/Avast/Norton/McAfee enabled as they can cause this as well.
3) If your computer is taking too long to get connected, then the server will give up and close the connection.
Those are the main reasons. There are many more, but let's start there.