bad ethernet port on new ARRIS TG1682G

A couple months ago my old gateway died and I started leasing a new ARRIS gateway from Cox. When I installed it I had some trouble getting my wired network to work, and eventually found that the first Ethernet port was bad. By swapping cables and equipment to various ports, it was determined only Port 1 was bad. Some time after that I tried Port 1 again and it worked. Since (at that time) I was only using three ports, I didn't worry about it. Yesterday I bought a NAS and it needs a wired network connection. Port 1 was dead again. Switching the NAS to another port got the NAS up, but now I need another port for the computer that was displaced. Sooo... Before I go to the trouble of tearing my system down again, I was wondering if there is something that cause this intermittent behavior or if it is just an intermittent problem and the gateway needs to be replaced. Last time I did this I did all the troubleshooting and setup work, and Cox charged me a "fee". I eventually got that fee credited, but I would like to avoid the hassles this time in the event I have to swap the gateway. Thanx.