streaming problems

For about a week or two now I have been unable to stream programs on demand or tv programs I have recorded or live TV on the xfinity site - either the app or at xfinity.com/stream. The streaming either doesn't work at all or only works for a few seconds then stops and buffers and continues this way - a few seconds play and then buffers. Sometimes the sound will continue but the picture stops. My internet speed is very fast, streaming works fine on all other streaming apps like Netflix etc. I am on a Macbook pro, using Chrome but I have tried on Safari and Foxfire and also on the app on my iPhone and the same thing happens. We have two xfinity accounts because we have two houses and this happens with both accounts whether we are on the home network or not for the accounts. I have tried clearing my cache numerous times. I have called comcast but they didn't do anything. Any ideas??? Before a week to two weeks ago I could stream fine - never any problem. the whole site seems to be running slowly - pages load slowly - like the TV schedule loads slowly but the streaming is basically nonfunctional.