ZBT2 with HA in VM in TrueNAS "Device requires a Thread border router"

[steep needle]

I am running HA in a VM inside TrueNAS. I've put in a PCI USB card which I throughput to the VM to make my Conbee II stick work. And that is working fine for my Zigbee network.

Now I've added a ZBT-2 and followed all steps from https://www.home-assistant.io/integrations/thread/#to-make-home-assistant-your-first-thread-network
I also tried "Set Thread credentials" from inside the Matter Integration, but that just gives an empty "Dataset" field.

Whenever I try to add a device (in this case Ikea Myggbett or Myggspray), it says "This device requires a Thread border router".

The ZBT-2 is recognized in HA and in the OTBR log it says "Role detached -> leader".
I also tried updating the firmware to the Beta version, but that didn't help.

Last thing I tried is asking ChatGPT, but it just made everything worse and kept whining about disabling TREL in OTBR. But there is no option to disable that. And I am not allowed to edit the YAML file.

My TrueNAS is in my main network VLAN and the HA VM is in my IOT VLAN.
I tried with my phone connected to the main network and with my phone connected to the IOT network, but both gave the same error.
Both networks can talk to each other and IPV6 is enabled and have access to the internet (apparantly that is required for adding devices to Matter too).

I also tried it as a Zigbee router instead of the Conbee II and that worked ok. But that's not why I bought it.
Did I forget to do something or is ZBT-2 Matter not supported in a VM?

[quartz magnet]

Homa assistant and the OTBR add-on (app) work fine in VMs. You need to make sure that your network is set up such that:

• your phone can resolve mDNS queries which are answered by the OTBR
• your phone receives IPv6 router announcements sent by the OTBR (check the ip addresses in the phone, make sure it has one assigned in the correct range)
  Due to these requirements, matter over thread basically doesn't work across vlans.

Just to confirm, do you see your openthread border router as the "Preferred network" in home assistant, and does it have the little rectangle with key icon beside it?

Also, are you using GrapheneOS? That does not work, can't be used for matter device commissioning (it blocks required google play services functionality)

[steep needle]

I am connected to the same VLAN as my HA. I can see the router as the preferred network and it has the rectangle with the key (after I clicked "send credentials to phone"). I did put that in my post, but I see now that it's not there anymore. Must've deleted it by accident.
I am using stock Pixel Android. And my ipv6 address on my phone starte switch the same number as that of my HA (2001:xxxxxx)
How do I test if my phone can resolve mdns queries?

[quartz magnet]

Ok, something is going wrong with the ipv6 router announcements then. you should have an ipv6 address from a ULA (starting with fd)

[steep needle]

I've read some more. Could it be my prefix delegation for ipv6 isn't correct? I have to call my ISP to ask if they can give me a /56 prefix. I still have to read some more, because most of it is still going over my head...

[quartz magnet]

Prefix delegation shouldn't be relevant, the tbr will advertise it's own ula subnet if it doesn't support or can't get dhcp6-pd

Wireshark on a laptop on that wifi to look for the router announcements from the otbr might be a good idea

[steep needle]

Maybe I found something here https://ndo.dev/posts/matter-thread "You do not need a public IPv6 address from your ISP to run Thread. Simply enabling support on your local router is sufficient." I'll be checking my networks later.

[steep needle]

Well, ipv6 is working correctly. Apparently it's the USB3 port that isn't working, I think. The led on the ZBT-2 was off, so I tried plugging it in a couple of times and after a while the light began to blink. According to ChatGPT it is because "The initial errors (error -71) are common with USB 3.0 ports or hubs; sometimes a device needs a direct USB 2.0 port on the motherboard to initialize reliably.". Is that true? I can't believe it won't work with USB3... Is this only with Matter? Because when I installed it as a ZigBee router and replaced my Conbee II it worked fine.

[steep needle]

Tried in on a HA install on a Raspberry Pi 5 and same error on my phone. Either the ZBT-2 is broken or there is something with my network. Gonna make a separate VLAN this weekend and test with that.

[quartz magnet]

the light on the zbt-2 should be off when it is operating correctly (i.e. when connected to a computer and working as a zigbee coordinator or thread border router)

[steep needle]

ZBT-2 is going back to the store. Tested on a seperate VLAN and still not working. I ordered a SONOFF Zigbee 3.0 USB Dongle Plus MG24. Hopefully that one will work.