Orbi RBK30 connectivity to AT&T Uverse Router

I am setting up my Orbi RBK30 for the first time, and I am connecting to my AT&T Uverse wireless router.  I have AT&T internet services only.  When I connect the Ethernet cable to the AT&T router, the light at the AT&T router connection is red/orange instead of green like the other Ethernet connections.  I have tried turning off WiFi on the AT&T router (and I've since turned it back on) and I connected a laptop to via Ethernet to the Orbi and have put the Orbi in AP mode but I continue to get the message from the Orbi app of "Orbi Network Not Found".  The AT&T router seems to be functioning fine, and when I turned WiFI back on the AT&T router, I can get WiFi internet service.  I have unplugged/restarted both the AT&T router and the Orbi router several times but to no avail.  Thoughts and next steps?