UniFi Controller not listing devices on OpenWrt router

I have a GL-MT300N-V2 router on which I replaced the factory OpenWRT with a plain version of OpenWRT. To this router, I have connected all my IOT devices via WiFi. The DHCP is done via the Ubiquiti USG so the OpenWRT router is passing the IP through.

I used to see all these devices on my UniFi Controller but they no longer appear. All I see is the router connected as a wired device (correct - connected on LAN side).

To make these devices visible, is this an OpenWRT setting I have wrong or a UniFi Controller setting/issue?

You want to set up the GL-MT300N-V2 as an access point only, so that it's not doing IP routing. These pages which seem to be duplicates explain it:

That is exactly what I have done. I now think it is a change at the UniFi end that is causing this.

@borpin, I too am seeing weirdness in a similar but different configs. Running a USG, UAC-AP and UC-CK on the 5.12.72 Controller.

I needed a wireless bridge and took a GL-AR300 and set it up in GLI's Extender mode (not clear what it REALLY is) and it shows in Unifi as an AR300 connected wirelessly to the UAC-AP, but the IP keeps changing depending on what device attached to the AR300 is sending traffic. It returns to one particular IP when idle (happens to be the last device with a static IP, not sure if its relevant).

Not satisfied, I took a Buffalo WZR-HP-G300NH and set it up as a wireless bridge with relayd and all devices show as connected directly to my UAC-AP. The Buffalo shows no where.