Repeater works but disconnects or remains connected but WPS problems

[Bothan]

The repeater is working for sure because I use a program (inSSIDer 4) to see that I have a 5 ghz signal. I also connect to the repeater and get MUCH better Mbps in the bedroom. (sounds dirty). Anyway after some period of a few hours the repeater stops working or remains working but the NVG589 (AT&T n router) WPS light blinks red and though in these cases the repeater can still be connected to, I cannot access it's settings online.

Any ideas? I see many threads about MAC addresses but I don't know anything about that topic. In the thread I understood that if there was a MAC address problem I wouldn't be actually connecting to the repeater and I KNOW I am (when it is working).

[Bothan]

EDIT: It happened again, I am still connected to the repeater, all the repeaters lights are indicating that it is working, but the router's WPS button is blinking red.