--had the connection problem this weekend. Turned out that my ISP solved it by replacing the COM21 cable modem with a DOCKSIS. The tech said the COM21 was not very good for "broadcasting" (luckily he was a p2p kinda guy).
He also routed me to a different hub.

So it was an ISP harware/network problem. Ask for a ping test to their DNS servers and see if they see packet loss and slow ping times. Only they know what's "Slow" for them.