U-Verse will freeze then drop completely stated No Network connected

Until couple weeks ago all has worked fine. Now, usually in the evening, U-Verse will stop completely by freezing the dropping the program all together. This happens watch live tv as well as recordings. It took me over 2 hours to watch a 1 hour recorded program last night as it would drop with error message "No network connected" constantly.

We will reboot the router. We will reboot the receivers (we have 3) many times during the problem. The internet works fine so it's just a U-Verse situation.  Suggestions???

Patsy