So you can connect to other servers fine, and you can connect to your server fine, but sometimes it kicks out? That makes me think
A. Your server is having a issue sometime, making it cut out.
B. There is something different with your server then other servers. And thats where the ticket comes in with the company you pay. You need to know if there is some sort of security they enable or specail port.
Also, just to be clear, the game files are local, but you still had to upload some sort of client to the server right? Has that been configured? If so how? This really should be alot easier then this, so I think were missing some crucial info,.