Arris SBG7600AC2 - one of the 4 ports is not working

My Arris SBG7600AC2 cable Wi-Fi modem has 4 Ethernet ports.  I currently have all 4 in use.  It appears the one I had connected to my PC for Internet connectivity has gone out.  I have no Internet connection in this scenario.  The green light is not blinking on this port, but is on the other 3.  I used a cable tester to make sure the Ethernet cable was good, and it is.  I plugged this cable in another Ethernet port (with blinking green light) on my cable modem and I get Internet connectivity to my PC.  When my Ethernet connection is to this apparently bad port, and thus I have no Internet connection, I can use the Wi-Fi connection to the PC and I am successful in getting an Internet connection, but I’d prefer a wired connection.

I can get around my issue by moving my wired connection to my printer to the Mesh network Ethernet port (which is using one of the good cable modem Ethernet ports), and then using that freed-up good/working port for my PC Ethernet connection.  But, I had rather have things the way they were.  I used the Ethernet “Troubleshooting” function on my Windows 10 PC when connected to the bad port and it says I have no Internet connection, just as you’d think.  I have not reset the Cable modem to the factory defaults.  My custom defaults are simple things (which I have a saved backup file for) like SSID name, password not the default, etc.  So, nothing that would be an issue to have reset with the factory default, and since I have a backup that would be an easy reinstall.

This issue just started today (no bad weather).  Any suggestions as to what might be the issue?  I have a combo individual battery backup (UPS) and surge protector for the modem, but if it is something akin to a lighting strike or electrical surge, and thus the port is toast, what’s my options?  Is there a way to test the port?

Thanks for the help.