A couple of my neighbor’s Hue lights are happily joining my ZHA network whenever I enable joining by going to the “add device” page. If I remove them, they will simply rejoin the next time I try to add a new device to my network. I’ve read that in Z2M there is a way to ban specific devices from joining the network. Is this possible with ZHA?
I realize that I could allow the devices to join but keep them disabled — but it seems preferable to not allow them to join in the first place.
Whatever the reason your neighbor bought expensive Hue light but didn’t add them to his setup, don’t allow his device to join your network, or he won’t be able to do anything with them unless he resets them.
Not possible as far as I know so suggest post a feature request here → https://community.home-assistant.io/c/feature-requests/13 as well as a question to ZHA and zigpy developers here → https://github.com/zigpy/zigpy/discussions
Actually I think the bulbs are just working on two networks at once, as long as they are different protocols. When I first got my Hue bulbs, I set them up using the Hue mobile app and Bluetooth. Then when I started building out my zigbee network, I was able to add them to zigbee with no trouble at all — but I can still control them with the Hue app. So I’m guessing my neighbor is just using Bluetooth (or maybe a Hue bridge?) to control their bulbs, which does not preclude the bulbs from hopping on to my zigbee network when I permit devices to join.
Thanks. I have posted a feature request here:
And posted in the zigpy discussions here:
I would connect to them, and do an automation to change state and color randomly. They will think they are broken, and do something about it.
That would be a good passive-aggressive solution and a popular suggestion for sure. I went with the more polite option of texting the neighbor to explain what was going on 
(Unfortunately I am not sure there is anything they can do about it themselves, if they don’t have a zigbee coordinator.)
I’d still do it, at least for a little while.
They deserve it because, Hue lights…
Maybe blink in Morse code…
If you think it’s a good idea, you should vote for it. I did…
Suggested Reading:
Feature Request Guidelines 
- Feature Requests - Home Assistant Community.
You could write a script to send a leave request to those devices and execute the script whenever some time after detecting that joining was possible (I suppose there are events for that).
My understanding is that once a ZigBee device is paired to the coordinator of a ZigBee network, it remains connected to that network and will not attempt to pair to any other ZigBee network. Therefore I agree with you that your neighbor is probably using the bulbs via Bluetooth only and they remain available to pair with any ZigBee network that advertises it’s available to connect new devices.
Until ZHA gets the ability to blacklist devices, you may want to discuss the matter with your neighbor and offer to give them a free Hue Bridge (in my area, Facebook Marketplace has them for as low as USD$11). Seems like a cheap way to eliminate the nuisance and build good will with your neighbor.
Ah, good one. I missed that Hue produced bulbs that could be used both on Zigbee and Bluetooth…