Wow. I have the openwrt router with the pitiful Sagecom Bell Fibe router (black one) acting as a bridge. All of a sudden I am horribly sensitive to the amount of connections, especially running bittorrent. Once that bug trips, you can ping, but you can't surf. It won't let through large packets.
This bug has been around forever, and I think it favours Bell, especially with regard to things such as ip phones. Why fix it? Anyway, I've clamped down on connections, and I keep upping them until it crashes. It is easily fixed by power cycling the modem. Only the regulator could get them to fix this convenient bug.
Update: Have confirmed that the bug is only activated during high congestion. Very convenient.
Update2: Actually triggered it early Sat morning. Am now trying a totally choked down bittorrent (updates :)
Solved! The bridge can only handle a packet size of 1434. Set your MTU on the Linux machine to that. So far it is stable.
Solved+1: I can still crash it with a huge number of connections on bittorrent. Cut those down, and it doesn't bother the speed.
Not really solved: This is definitely an attack from Bell (intention or neglect). I can't run anything reasonable without hitting the bug. I can just hit it really fast or slow.
Blah: I ended up severely cutting down the connections to 30, and gave up on all the extras like DHT. Now it is stable, and I still get some good speed. So I don't know if the MTU thing was relevant.
Up7: As stated in another post, my complaint to the CRTC resulted in my being switched to a clean channel. I can run it with factory default. Won't last long.
January 17, 2016. The final solution to this was to beg for the new 'white' bell 1000 modem. I also have a fast router running openwrt, and when it connects to this modem, the modem automatically goes into bridge mode. Paradise.