Does you're ISP throttle P2P? If they do then bitcoin-qt downloading the bloackchain for the first time will look like you are downloading a large torrent file causing them to throttle the speed.
I've seen ISP's that throttle P2P down to 0.5 kpb/s before causing the program to time out.
People download torrents all the time here. They block VPNs and Skype though.
But the odd thing is that it's the mesh wireless network that dies, not the dsl box. Data through the dsl box is fine.