Please help with Orbi Setup for AT&T Pace 5268ac and iOS unable to download from app store

I initially followd the orbi directions to connect the orbi into one of the ports in the pace and hook up the satellite. I initally got everything hooked up and working but for some reason after connecting to the OrbiWifi I realized that I was unable to update or download any apps from the App Store and would get an unable to download error but then I would switch over to the regular WiFi from the pace everything was fine. I'm not sure what I'm doing wrong. I seen a couple posts talking about DMZ mode (which I don't understand how to do). I've been researching for hours and cannot figure out why I'm getting this bug with the App Store and what the proper way to install the Orbi is with the pace with steps. If anyone could help me. I would greatly appreciate it!!!

Thanks!