Question on setup

Hi all ... I have a congestion issue which I'm trying to resolve before the folks in our house fire me. lol

Size: 3k sq. ft

Layout: Lengthy single floor (long distances from end to end)

I currently have an Orbi RBR760 which I purchased at Costco and doesn't manage congestion well (apartment building next door and highly congested Wifi (16 networks show up when scanning). I've turned on a DFS channel (local airport does not use DFS radar), which has helped but when connected to the Orbi satellite throughput is much slower than the router (1-2Mbps vs 400+Mbps).

I got a suggestion to look into Ubiquity for its ability to manage congestion well. I'd like to get comments on whether the following setup is the way to configure Ubiquity equipment:

Internet -> Dream 7 Wifi Router

Dream 7 Router -> POE Hub

POE Hub -> Ethernet run to other side of house -> POE Ethernet Splitter

POE Ethernet Splitter -> U7 Pro Wall AP

Will these two work together? Would setup for the U7 Pro Wall be straight forward as an AP to the Dream 7 router?

Also, is there a specific setup configuration that is a best practice for a congested Wifi spectrum?

Thanks in advance!