The UAP-AC-Pro is their greatest piece of hardware. Used on eBay for $70

Internally, it is a switch with 2 physical nics & 2 wireless nics attached to 1 cpu with zero interface abstractions in between. If you flash OpenWRT on it, it becomes clearer that it’s a nice piece of hardware.

Delete all the OOTB networking, attach PoE to pnic1, WAN uplink on wnic1, LAN downlink on wnic2 & pnic2. This will give you a private network where your physical and wireless clients can talk to each other.