Bad router port

Hi all, I have a Technicolor CGM4331 modem router.  I use my own router so the modem/router is set to bridging mode.  This set up has worked great and I don't have any complaints about Cox's internet service.  Yesterday my internet connection started failing intermittently.  I'd have internet for awhile and then I wouldn't.  It finally stopped working altogether.  I switched the internet connection to another port and everything has been working fine.

The original connection was in the lower port over the power plug, I switched it to the upper port over the coax cable connector.

Let's assume the port was bad and that my remedy was the correct fix:  (1) Can I continue to use the Cox Modem/Router or (2) Is the bad port indicative of something that will affect the other ports? Thanks.