This error page is caused when the servers drops the connection to your client because too much time has passed between the initial connection being established and the transmission of data.
A large number of potential issues can cause this problem, including load on the client matching, issues with your local area network, issues with your ISP, issues with the route to the server, and lastly it could potentially be caused by high load on the server itself.
If you receive this error page, it is recommended that you first check your traceroute for any issues or delays:
