Screen freezes on the DVR box TV

Can you provide additional details as to how your DVR is now connected to the Gateway?  Describe any intervening equipment (such as switches, bridges, etc.) and cabling (cat5e, etc.)

Catt 5 now, formerly coax.  We had a router going bad and needed an upgrade.  The newer units are not coax friendly, so we had new lines dropped for the three wired boxes.  We have noticed that it doesn’t do it on low definition channels, only HD ones.  I switched the DVR with another box and it still does it on HD.  It doesn’t appear to effect any of the wireless boxes in HD though.

Do all of your wired boxes connect directly to the new Gateway, or do they connect through something else (e.g. an Ethernet Switch or third-party router)?

Is this Cat5 or Cat5e?

Are the runs very long (> 50 feet)?

Are all 4 pair (8 connections) being connected at each jack/plug?

The tech ran cable through the walls and attic down to a Ethernet plug near the router.  The router is connected to that plug and all are directly connected to the router.  The farthest is about 35 to 40 feet.  I believe the cable ran might be cat 9, but I am not a tech and I am not sure.  There is absolutely no aftermarket equipment used.  The only people that have done any work has been AT&T technicians.

So, what you're telling me is that there's a single RJ45 jack by the AT&T Gateway, with a single Ethernet cable to the Gateway.  And there are multiple RJ45 jacks in different locations throughout your home, each connected to a different AT&T TV Receiver (one of these Receivers being your DVR) via an Ethernet cable?

Is that right?

My wife has confirmed that this only occurs when we watch HD channels in the living room.

@KGJones 

Interesting to hear att is still supporting customers to convert from coax to Ethernet.   Presumably the tech used an Ethernet switch in your attic to distribute the signal to each room.  Just based on the information you provided, I’d surmise the cable run from the switch to the living room has a problem.  
I’ve actually experienced this myself on an install done by an att tech.   Ended having to redo the RJ45 connections on both ends of the cable myself.  The only “good” that came out of it was getting a wireless settop box. 🙂

@KGJones 

So, what you're telling me is that there's a single RJ45 jack by the AT&T Gateway, with a single Ethernet cable to the Gateway.  And there are multiple RJ45 jacks in different locations throughout your home, each connected to a different AT&T TV Receiver (one of these Receivers being your DVR) via an Ethernet cable?

Is that right?

Interesting to see this thread resurface with another phantom userid.  

I wonder whatever happened with the OP.
@KGJones ???