The solution

Well, being slightly paranoid and not wanting arbitrary folks logging into my router, I wanted to find a way to protect myself. I also thought the router manufacturer or ISP employees may give out the admin password for this strange port, then it hits the intert00bs and catastrophe...you know, cats and dogs blah blah.

So here's what you need to do if you own one of these routers:
1. Remove the router.
2. Remove the COAX conection from the ONT (Optical Network Connection)
3. Call your ISP and have then enable the Ethernet connection in the ONT.
4. Connect your favorite router to the Ethernet broadband ONT connection
5. Put the ISP's router behind your router
6. Keep the COAX connection from the ISPs router to the STB (Set Top Box) to maintain program information and monitoring of what you watch…..(or just leave it disconnected and use your TIVO, MythTV etc. for program information)

That doesn't turn the port off but at least makes it hard to get to from the outside. Time to do some deeper investigation.