AT&T receivers connect with the U-Verse Internet protocol television network. The receiver does not contain a conventional tuner, but it is an Internet protocol client that requests streams that you desire. In this model, only the streams (channels) that the customer requests are sent to the television. The drawback of AT&T's model is that the picture can freeze from time to time from interrupted streams. To fix this problem, you have to reset the receiver.
Press and hold the "Power" button. It is on the left side of the receiver. Hold it down for about ten seconds.
Release the "Power" button. It will take about two minutes for the cable box to reset. This should establish the connection to the U-Verse network.
If the soft reset does not work, unplug the receiver from the wall. Wait about 15 seconds and plug the receiver back into the wall.