I bought the Deco routers to replace my aging Orbi routers which I had switched to being access points in the years past because they kept locking up. 

My goal with this purchase was to use the Deco as my true router so I can have parental controls and change my DNS to an internal machine (PiHole) to block ads on the network.(The BGW320 does not allow custom DNS servers) 

The problem I am facing is that the Deco router is not being given a true external IP address from the ATT Router, the "IP Passthrough" function does not appear to actually do anything. 

On the BGW I have changed the following

1) disabled wifi

2) Turned off all firewall functions

3) Disabled packet filters 

4) Enabled IP Passthrough

The Deco is still being served up a 192.168 IP address from the ATT router. Which is causing network slowness and the dreaded double NAT

Things that stand out

1) If you look online about this.... half of the posts say it's easy just set up IP passthrough. The other half say it's not possible. 

2) I believe routers have 2 MAC addresses? The sticker on the bottom of the Deco state that the MAC address ends in "50" but in the BGW320 it sees it ending in "51". I've tried both. neither seem to work

Has anyone actually been able to get this to work? Or is it time to give up and return these Deco routers?