Two days ago my internet started disconnecting and reconnecting at random intervals. It would connect for a couple minutes maximum, then disconnect.

As far as troubleshooting goes, I power-cycled the modem first and foremost and that did nothing. Then I bought and installed a new modem and that also accomplished nothing. I returned the new modem and changed out the coax cable because a small part of it is damaged/frayed. That also did nothing. After that I pressed the reset button (probably should have been the first thing I attempted- whoops) on the modem itself and that fixed the problem, albeit temporarily. The internet worked fine last night, but now it's doing the same thing it did two nights ago. And I have pressed the reset button again, but now it's having no effect whatsoever.

Note: I did also call my ISP- Comcast- and they did their own troubleshooting (sending the modem a signal and pretty much that's it) and also confirmed that I am not experiencing a service outage. The modem is an Arris SBG6580 and I purchased it over five years ago. I doubt that using a Comcast-issued modem is going to make any kind of difference either. That and I don't want to pay Comcast to rent one when I can just buy one online right now.

Any suggestions?