OTBR sees ZBT-2, adding device shows "requires TBR"

Configuration Matter/Thread
1

I’m a newbie.
I added ZBT-2 to HA to be a thread border router. I’ve worked through some problems, but now when I attempt to add a thread over matter device, I get the error “Your device requires a Thread border router”.

OTBR shows “Home Assistant Connect ZBT-2 (OpenThread Border Router)”.

So what does it need that isn’t already present?

I see the following in logs:
2026-03-31 20:31:21.840 (MainThread) INFO [matter_server.server.server] Matter Server successfully initialized.

Default: mDNSPlatformSendUDP got error 99 (Cannot assign requested address) sending packet to ff02::fb on interface fe80::5ca0:c5ff:fe5b:daa4/vethf8bbda5/18

Thank you so much!

2

During commissioning, in general the phone you use to do the commissioning, as part of the commissioning, the phone is looking for mDNS advertisements coming from the new device via the OTBR. When it doesn’t see these, it thinks that there is no TBR, when what is likely happening is that the phone does not have the correct Thread credentials to give to the device and thus the device is not actually able to join the Thread network.

If you believe the phone has the correct credentials, then the other cause is often that the phone is on a different network than the HA/OTBR.

3
  1. From the OpenThread border router, have selected “Use router for Android + iOS credentials”
  2. From your phones Home Assistant mobile app → Settings → Companion app → Troubleshooting → Sync Thread credentials

Try both of those steps to be sure