I have Comcast Internet (over three yrs now). Several months ago, I started to lose connecvtivity for no reason. Everything is green on the cable modem and rouiter. I just lose Goggle or any other website. If I turn the power to the modem off and on - I regain connectivity for five minutes to 24 hours (seems random except that shorter time on weekends). Is this a problem with Comcast's system?