loss of direct tv signal

What streaming devices? What error code do you get? Does this affect mobile devices as well? Have you tried restarting the device?

Direct TV stream

As i understand it ATT has wired my apartment with a modem and router

Assuming you are using the DTV Stream streaming device - the one I have occasionally loses WiFi connectivity, and no longer sees the network (even though other devices do).  In those cases, I have to reset the device, by pressing the red button on the side (just momentarily - a long press does more serious things).  It normally then will come back and connect, though it usually takes a couple of minutes.