Server connection problem :/

Now, everytime I tried to open this server, it often just open and timed out, sometimes even timed out after the "logging in..." page. It made me so frustrated. Furthermore, I can open other server just fine, with good connections. But i came back on this server it just "BOING" me out. Why is that happening to me? is it my router's problem? This issue has been happened to me weeks ago. ;-;