Uverse no signal

I have fiber coming into my house to the gateway....ethernet cables from gateway  to...my pc, to a WAP for the wireless connection for my upstairs TV,

and one to the DVR...with an HDMI cable to my Vizio 50 series TV.

My problem is only with the: gatewy-dvr- vizio connection, with that one I am continually getting TV no signal and the restarting process starts, many, many times.

I have had the Gateway replaced and I have used a new HDMI cable between dvr and tv and new ethernet cable between gateway and dvr. (also, changed to different hdmi ports on my tv), even tried hooking up a different TV to the dvr, same issue.

None of this has made any difference...what the heck is next for me.....besides cancelation.