Matter over Thread: some dumb questions

[smoky ledge]

I’m running Home Assistant OS and trying to nail down how Matter over Thread fits into my setup:

Installation Method: "Home Assistant OS"
Core: "2025.7.1"
Supervisor: "2025.07.1"
Operating System: "16.0"
Frontend: "20250702.1"

• Device: A Matter/Thread gadget that pairs just fine with my Google Home Nest (2nd Gen).
• Current Border Router: Google Home Nest (2nd Gen) — my Thread devices pair fine there.
• Problem: I can’t add the Thread device to Home Assistant via the native Matter integration. I've tried both pairing it directly using the HA Companion App and sharing it from Google Home, but it always fails at the last part, see the attached image (translated:

Add Matter Device.
Unable tto add the device to Home Assistant. Retry?

My questions:

• Do I need a dedicated Thread radio (e.g. ZBT-1 or equivalent) attached to my HAOS host to be able to pair devices, even shared from the Google Nest TBR?
• Or can I simply use my Google Home Nest Gen 2 as the Thread Border Router and have HAOS pick up devices through that?
• If a ZBT-1 (or similar) is mandatory, does anyone have some suggestions for radios other than ZBT-1? In italy is hard to find and the one I've found are overpriced.
• Are there any known workarounds to proxy Thread traffic from the GHN router into Home Assistant without extra hardware?

Any pointers, links or personal experiences would be massively appreciated!

[dim latch]

No you dont need a dedicated Thread radio. You can use google nest as a tbr and add devices to home assistant over that. When you want to use a seprate tbr in home assistant i would recoment a smlight poe. You can get them cheap over aliexpress.

[smoky ledge]

Thank you for the response! Then I don't understand why it's not connecting to my HAOS instance. In Google Home it's working without an itch, but fails when I try to get it to get added to HAOS. From the logs I only get these lines and nothing more:

2025-07-11 18:32:42.391 (Dummy-2) CHIP_ERROR [chip.native.EM] <<5 [E:29780i with Node: <0000000000000000, 0> S:0 M:229476284] (U) Msg Retransmission to 0:0000000000000000 failure (max retries:4)
2025-07-11 18:32:52.831 (Dummy-2) CHIP_ERROR [chip.native.SC] PASESession timed out while waiting for a response from the peer. Expected message type was 33

Also, my Google Nest is the only Thread network and is the preferred one

[clever dagger]

Have you imported the thread network credentials from your Nest Hub into your Home Assistant companion App? Android:
Settings>Companion App>Troubleshooting

[smoky ledge]

Yes, already done that

[clever dagger]

Hmm, since you mentioned it above: If you already have the device in Google Home the only supported flow to add it to another fabric is to share it from the pre-existing one. You cannot reuse the original pairing code.
Some matter devices have a bad multi-fabric implementation. You could try and remove the device from Google Home, reset the device, pair it to HA (using the original matter code), and from there share it back to Google Home. Maybe that works. If you can pair with HA that way and still can't share back to GH, your matter device lacks proper multi-admin capabilities.

[smoky ledge]

Just to be sure, you suggest to reset the device (Nuki Ultra) to factory and try to pair it again to HA, because removing it from GH and trying to pair it from the original pairing code may not work?

[clever dagger]

Exactly. In some cases removing the device from a fabric might not also remove the fabric from the device, and if that happens the device will not become ready for pairing with the original code.
On the other hand: In my experience I never had this kind of issue with a Nuki product so far, and it should only fail, when you remove the device while being offline in the respective fabric. That said, you can of course try to execute the steps above without the factory reset, and if that doesn't work, you can still do the factory reset later, and then try again.

[smoky ledge]

I've already tried both disconnecting it from Google home and then connecting to HA and connecting from GH to HA, but I miss trying to connect it directly after factory reset

[smoky ledge]

Nothing to do, same error 😭