Don’t return the RB750Gr3. It’s the best router for the money by a long shot.
What people think of as a “router” these days is really probably 3 or 4 separate products:
- A router (in the literal sense, or a NAT gateway)
- A switch
- A WiFi access point (which is fundamentally a layer 2 activity)
- A firewall
(Not to mention DHCP and server, DNS relay (cache?), among other things. Not all of these things necessarily have to to exist on the same hardware.)
But this gets missed, because there are hundreds of questions on this forum about how to use multiple “routers” when really all they are asking is how to use multiple WiFi Routers as multiple WiFi access points.
Connect the non WAN port of the “WiFi router” (to be used as an access point) to the non WAN port of the RB750Gr3, and turn off the DHCP server on the Wifi router.
Done.