My connection has gone from completely lag-free 150ms to jittering between 150ms and 900ms constantly throughout the game.
It even seems as if packets are coming back in the wrong order (although this could just be a side effect of certain packets getting delayed a lot).
I'm guessing there is a bad link thats dropping packets somewhere en-route to the server or causing random jitter. I've tested on a Vodafone connection, and it works fine.
The server address is 126.96.36.199 but its not pingable unfortunately, just wondering if others have had the same issue.