Cannot connect Nuki Smart Lock 4.0 Pro via Thread using Home Assistant Connect ZBT-2

Nuki Smart Lock 4.0 Pro is Matter compatible and supports Thread, so I tried to add this to Home Assistant.

What I did so far by following this documentation: https://support.nabucasa.com/hc/en-us/articles/31347105826077-Forming-a-new-Thread-network-with-Home-Assistant-Connect-ZBT-2

  • Installed Home Assistant OS on my Raspberry Pi 5 (Core 2025.12.0, Supervisor: 2025.12.2, Operating System: 16.3).
  • Connected a ZBT-2, added “Home Assistant Connect ZBT-2” integration, selected “Use as Thread adapter”, waited for firmware update to complete and finished setup by changing device name to “Home Assistant Connect ZBT-2”. Firmware version is now 2.4.4.0.
  • Checked settings of the Thread integration: it only shows one preferred network “ha-thread-…” with an info icon on the upper right which on click shows details like e.g. “Channel: 15, OTBR URL: http://core-openthread-border-router:8081, TLV: …”. It also shows one border router “Home Assistant OpenThread Border Router …” that is suffixed with a door+key icon.
  • Checked “Open Thread Border Router” integration. It only shows “Home Assistant Connect ZBT-2 (OpenThread Border Router)”.
  • Installed and started Matter Server add-on.
  • Using an iPhone with iOS 26.1 and current Home Assistant Companion App I went to settings of Thread integration again and tapped on “Send credentials to phone”. The latter shortly displayed an activity indicator and then a check mark.
  • Then opened the “Nuki Smart Lock” app on my iPhone, went to Settings → Functions & Configurations → Smart Home → Matter and tapped the “Activate” button there. This shows an activity indicator for about 30s, then the Smart Lock’s LED ring turns white and a message gets displayed that I can now navigate to my Smart Home app to add the device.
  • Then go back to Home Assistant Companion App, go to Settings → Devices & Services → Device tab and tap on “Add Device” button. Select “Add Matter device” → “It’s new” and after that scan the lock’s QR code.
  • The QR code gets scanned correctly and a bottom sheet appears that shows a button “Add lock to Home Assistant”. I tap that button, then for about 2min an activity indicator is being shown and then in essence “Cannot add device” and “Home couldn’t connect to this device”.

Only thing I noticed in Matter Server’s logs is:

2025-12-04 22:13:42.591 (Dummy-2) CHIP_ERROR [chip.native.DIS] Failed to advertise records: src/inet/UDPEndPointImplSockets.cpp:417: OS Error 0x02000065: Network is unreachable
2025-12-04 22:13:42.596 (Dummy-2) CHIP_ERROR [chip.native.DL] Long dispatch time: 137 ms, for event type 2

But after these log entries I can see these:

2025-12-04 22:13:42.607 (MainThread) INFO [matter_server.server.vendor_info] Loading vendor info from storage.
2025-12-04 22:13:42.615 (MainThread) INFO [matter_server.server.vendor_info] Loaded 376 vendors from storage.
2025-12-04 22:13:42.615 (MainThread) INFO [matter_server.server.vendor_info] Fetching the latest vendor info from DCL.
2025-12-04 22:13:43.213 (MainThread) INFO [matter_server.server.vendor_info] Fetched 375 vendors from DCL.
2025-12-04 22:13:43.213 (MainThread) INFO [matter_server.server.vendor_info] Saving vendor info to storage.
2025-12-04 22:13:43.219 (MainThread) INFO [matter_server.server.device_controller] Loaded 0 nodes from stored configuration
2025-12-04 22:13:43.226 (MainThread) INFO [matter_server.server.server] Matter Server successfully initialized.

Already completely restarted Home Assistant by selecting “Restart system” and also restarted the lock.

So any help how to fix this and being able to add the Nuki Smart Lock would be greatly appreciated.

Only the 5. G n lock is listed though.

related iOS 26 Matter registration not possible - #13 by Cornelis - Matter - Nuki Developers

Had a look at thread mentioned by @jhol-byte - but renaming HomeKit Home to a single word term and charging Nuki Smart Lock battery did not change anything.

I’d like to know if those CHIP_ERROR log entries from Matter Server could be the root cause or if they can be ignored as the last log entry from starting Matter Server states “successfully initialized”?

The Matter server outputs so many warning and errors to logs and I think only the devs have just a bit of knowlledge to actually know the reason for some of them.
The rest of us mortals are just clueless and cross our finger clows our eye and pray a bit to the big IT god.