Ubiquiti - Unifi

I have a location where I can’t connect 2 places with a cable so I have set up 2 openWRT routers where one is working as a router and another one is connected to it via WiFi. The second one has WiFi bridged to Ethernet ports on it, so the connected devices are on the same network. Assuming I’d get a UX7 to replace the first one, how would I bridge the other place/what equipment could I use?

I have 100/40 fibre internet. Part of our house including my office was water damaged last year. So I moved my office to our guest house and needed internet out there.

Initially I set up a bridge using a UAP-AC meshing a hdnano but found the results pretty meh on speeds roughly 1-5mbps.

I decided to run a temp cable under the house and put my U6LR at the end of it and aimed it from under the room the hdnano was in at the UAP-AC and the results were pretty impressive.

Initially I was getting max throughput but it seems like it's now settled into "the speed" and has dropped.

Has anyone seen any odd use cases where they've gotten unexpected results?