I have had techs come out, talked with support on the phone and their internet chat.. It just all of a sudden started happening a few months back and I don't know what it could be.
Start with the modem's signal stats. Perhaps they already are, or they are close to being out of spec and intermittently they go completely of spec. Try getting them here http://192.168.100.1 or here http://10.0.0.1
Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.
What is the exact make and model number of the modem ?
Is this with a WiFi connection ?