Where are all you from? I'm in AZ and our internet has been finicky for the past few months. Been through that whole thing about reset the modem, oh and it's old and you probably need a new one... Which I got uppity with the rep about cause you don't just replace $100+ thing just because it's old. Had a tech come out a week after we scheduled, he re-crimped some coax ends, and actually made it worse. I think either their network gear is over saturated or having issues in some way and don't want to admit it. We pay for 300mbps and right now I'm getting 74mbps... I work in IT and I get it, but you should probably just be real and explain the issues you are facing and not hiding it.
We actually have two cable modems in this house, one is brand new, both running off of the same coax from cox and both experiencing issues so no it's not my equipment...