How to setup DMZ+ on PACE5268 and use a Netgear Router for all WiFi Devices

We have over 70 devices on our network including over 25 WiFi devices.  After partially implementing smarthome the network WiFi network bogged down, TVs glitched and LAN devices were continually dropped and added back.  To remedy this behavior, ATT techs advised we add a router to handle the WiFi.

Bought the Nighthawk and followed instructions found here on the forums and after several tries with no success I am trying to find better instructions.  

For reference, we have ATT Uverse and Internet 1000 on fiber.

Thanks