Over the last year I've been dealing with constant internet flapping. Multiple service techs have been sent out to try and remedy the issue to no avail. It wasn't just with this modem. Prior to this I had the Cisco brand of modems which I had flapping problems with as well. We've tried 2 Cisco modems, and recently had a service tech come out to run some new lines (not throughout the entire house, just off the line running in to the house) and swap out the Cisco modem for the Motorola Arris SBG6782, alas the problem is not fixed.
When these flaps happen the lights on the modem remain on but I lose connection to any program or video game that requires it. If I'm on Skype I'll notice that I go Offline for a few seconds, and then reconnect. If I'm on a call it temporarily drops and a few seconds later it reconnects. If I'm on a video game that requires an internet connection I'll get disconnected and have to re-load to get back on. Just today my net flapped at least 5+ times over the course of a few hours.
I'm starting to get beyond frustrated.