Yes but that made no difference.Levels seem decent, so doesn't seem to be an issue with the transport.
Have you tried bypassing your router and dhcp direct to the internet? I've heard older consumer routers are having a hard time keeping up with now typical 100mbps speeds, maybe it's just getting long in the tooth there too.
I've heard about the time 10 or 11 years ago they spoofed packets to kill bittorrent sessions as soon as they were started. They denied it repeatedly until somebody had done the research and caught them in the act. My own experience with them and this message from you inspired me to put this picture I found recently. I host it on a dinosaur somebody gave me. http://ladmo.asuscomm.com/comcast.htmlOtherwise, it *is* comcast, the most consumer unfriendly isp out there, and loves to use packet shapers to throttle users down. Perhaps they don't like your using all your bandwidth and feel you need less, as they tend to do this with netflix, youtube, and other bandwidth intensive applications already.
It could just be peering congestion too, I've seen it with cox here periodically. I can usually tell running an mtr to something like google.com, and watching for packet-loss and increased latency at the different peering hops. I tend to call a buddy that works there to harass him why their service sucks, and tend to hear back on some bandwidth augmentation processes going as a result, though ymmv with standard support as they'll have no idea, so just escalate otherwise if you see something like.