Thanks for all the suggestions guys. I went with Wireshark mostly because it was the first one suggested. It showed a TCP problem. Further investigation showed that parts of full size packets were being lost. At work, we recently changed the router. This was over the VPN and the first time I tried it that way since the changeover. Reducing the MTU of my connection allows me to work from home again. Hopefully our IT consultants will be able to figure out what the router problem is (bad MTU setting, no MTU discovery, ...?) and fix it. Worst case is a little network performance is lost over the VPN.