The power indicator light on the router is red

Red - Power light / Green - Wireless light?
I was told By AT&T the modem was bad and I needed to buy a new one.
My girlfriend had the same model and was not using it.
So I tried hers with my power cord and got the same thing.
I called AT&T back and they said her's was bad too!
Then I changed to her power cord and it now works. It is the power adapter!

The stagnant red-power indicator suggests the modem is already worn off, usually after one and half years of use. You can try changing the original power adapter with the PSP one.

Hope it helps =)

That is a indication that the device is getting bad , first thing that you can do here is to reset it , by unplugging the power fro about 30 minutes and check if the light will be back to green but if still the same you can also reset the device by pressing teh reset button for 30 seconds while power is ON then if still power is red the device is already bad....