Downloading Terrain.... Server closed

Hello guys, i have a problem. I was playing on a private server(Mindcrack like) when i waas going trough the portal for the nether. When i was downloading terrain, it disconnected me from the server. I tryed to join again, but it gives me an error :

Logging in ---> Downloading Terrain -----> Connection lost: Server Closed.
After this problem, i get another error : Connection lost : Timed out. I can't play on Mineplex(i am playing for 10 minutes and then - connection lost:timed out.

Please help me ! This stops me playing on my favourite servers.