It's usually a networking issue where the router is having issues. The traffic is simply being sent wrong through the network causing disconnects.
People have had very different solutions. Sometimes removing the power from the networking equipment for 5 minutes work, sometimes you have to toggle UPnP in the router, sometimes disabling DHCP and assigning static IP addresses have done it. Sometimes buying better networking equipment or buying public IP addresses have solved the issue. What have you already tried to solve the issue?
