Wired connections from modem doesn't work but wireless does.

Hi I am new here and I need help. I can normally figure out things for myself but this problem has got me stumped. I have an issue with the modem(s) I am using. My network has a modem (from AT&T uverse ) with a Cisco router connected to it through a wired connection and everything in the house connected wirelessly to it except my desktop. Yesterday I was disconnected from the Internet but all the lights on the modem were still green. I lost both wired and wireless connection. I tried the normal reset of the modem and it didn't help. All lights green. No internet connection. So I tried to connect to the wireless signal from the modem and I was able to connect to the Internet. So logic would dictate that if the wireless signal in the modem works and anything connected through wires ( wireless router, desktop) doesn't, then the modem would be bad. So I just happen to have another modem, exact same make and model. I connect it thinking this would surely fix the problem and it's the same problem, nothing is changed. Wireless works, wired doesn't. So now I'm stumped. I don't know what else it could be. It might be possible both modems are bad and have the same problem since it's the same brand and model but I want to explore all possibilities before I call AT&T and deal with their lousy service.

From what you said, In both modem wired connection did not work, which means that you should try to change the Ethernet cable and verify that there is issue in the cable itself.
Hope that helps. :)
Regards

I would also check that cable.