How frustrating, one of the cool things about Unifi and their older product line is how they manager zero handoff. This is needed because most clients are stupid. They hold on to a wifi signal for way too long. What you want in a good environment is for there to be enough coverage (without interference) to sectorize your wifi.
With the older UAP-Pro and UAP lines, they used Atheros and could do this. They all worked by using the same Mac ID and then managing who connects from the Unifi controller. This is a great solution.
The problem is that the new UAP AC use Broadcom and do not support zero handoff. So you get this problem that if you connect to an access point on one side of the room, then if move to another room, you will still be connected.
They have been promising an update for a year (?!) now and it hasn’t shown up. But there is a workaround. You can change the RSSI minimum for each AP. This means that if you see a low relative signal strength, it will kick the client off. It’s a decent solution for now as the UAP AC are the only ones where there is any hope for a relatively cheap price of getting this kind of handoff.
It involves some heavy hacking of files, but it should work pretty well.