Connecting ASUS router to BGW320-500

You do not want Access Point mode on the ASUS.  As ASUS says here 

In Access Point(AP) mode, router connects to a wireless router through an Ethernet cable...

You want Repeater mode:

In Repeater mode, the router wirelessly connects to an existing wireless networks to extend the wireless coverage. 

The app does not allow for repeater mode. How do I switch to that mode?

thank you

Hm... my AC1900P supports it, I assumed yours would do.  Perhaps its because I have the Merlin firmware.

Let's get you pointed in the right direction to set up your 3rd party equipment, @andre2117. 

Thanks for your advice, @JefferMC!

You'll want to reach out to the manufacturer of your router for more instructions on how to do this. You can also use our paid service, HomeTech, for more advice. 

If you have any other questions, please let us know, Thank you for contacting AT&T Community forums.

Raiden, AT&T Community Specialist 

@andre2117 

Don’t call hometech. Sign into the router using a web browser. Repeater mode can be selected there. 

@browndk26 ive read over a bunch of forums and am still a little confused. 

if I am just wanting to extend my signal upstairs using the provided bgw320 as the primary source of internet, should I use my ASUS router in repeater mode or access point mode? I have cat 6 wired to spots upstairs where I could hardwire the asus router, but am confused if I will have two separate WiFi networks if I use access point mode. 

thank you!

Access point. Give the asus the same network name and passwords the gateway Wi-Fi.