CM500 Losing Connection

I have been having an intermittent internet (Comcast/Xfinity) connectivity issue over last ~2mo. especially in the evening for 5-20min. durations. The internect connection would always come back at some point, so I never bothered contacting the ISP.

Yesterday, I have completely lost internet for about 4 hours. After completing a complete reboot/factory reset of the modem (CM500), I started to get intermittent internet connectivity... (instead of intermittent internet connectivity loss)

On the modem, I get continuous steady blink of green light on the uplink. When I check the cable connection via Netgear Genie, I see only 1 channel is locked and 3 are "Not Locked" (See attached image)

Is my Netgear Modem dead and requires a new equipment or is it the connectivity issue (i.e. coaxial cable) that is causing the problem?