Comment 23 for bug 411688

I just encountered this same symptoms today in my newly upgraded ubuntu (from LTS 12.04 to LTS 14.04): 100-150kB upload to 224.0.0.56 and my wifi down to less than 1Mb effective bandwidth.

There were a few updates today which seem to have triggered the behaviour, as I had no problems before the update.
But I cant seem to find the update history so I can't tell you which packages - it included a kernel update & reboot. I'm now running 3.13.0-24-generic.

Disabling rtp-send as per #5 works around the problem - and I'm not planning on streaming any audio any time soon.