Configuring the Orbi RBK752 kit with an at&t Fiber BGW320-500 Gateway

Hello everyone,

My name is José.

I am a new member.

I am seeking advise from anyone here that can help me with the setup and configuration of an Orbi RBK752 system with an AT&T Fiber Modem/Router BGW320-500.

My home has a main ground level floor and a basement.

When it was built a few years ago it was wired with high-speed Coaxial and Ethernet throughout. 

The Distribution Wiring Panel is in the basement.

The AT&T Fiber Gateway is also in the basement. The AT&T installer brought it in from the AT&T junction box on the street to the distribution panel in the basement. 

The Orbi RBR750 Router will be in the main floor above the basement, and will be connected to the AT&T Fiber gateway via Ethernet cable through the structure.

The WiFi signal from the Fiber gateway in the basement is very weak on the main floor, but still detectable. 

I don't want to have two separate WiFi networks broadcasting and conflicting with each other. 

I have read different opinions on the internet about what the best configuration should be.

I also spoke with Netgear's Tech Support, and was told there are three ways to do this:

1) Put the AT&T Router in Bridge Mode.

2) Turn-off the AT&T Router's WiFi radio.

3) Leave the AT&T Router alone as it was configured by the installer, and configure the Orbi Router with the Mobile App.

I am a bit confused as to which method will work most efficiently.

If anyone here in this community can shed some light on this subject, I would greatly appreciate it.

Thank you!

Best regards,

José