Struggling with Matter over Thread – unstable OTBR setup and connectivity issues

Configuration Matter/Thread
1

the longer I’m using Matter over Thread, the more issues I’m running into – and it’s getting quite frustrating. I’d really appreciate some guidance or insights on how to move forward from where I’m currently stuck.

Initially, I started with an OpenThread Border Router and a Sonoff ZBDongle-E 3.0 (EFR32MG21). Everything worked fine — two Eve Door Sensors and a Nuki Smart Lock 5 Pro were operating reliably.

After moving to our new place (a bit larger), my Home Assistant server (HAOS 2025.10 running on a Proxmox machine) now sits in the basement — not exactly the ideal location to cover the entire house with a small USB stick. As a result, I started experiencing random connection losses with the smart lock — surprisingly, not with the Eve Door Sensor right next to it (on the first floor).

My next idea was to add another border router, ideally a PoE-powered device. So I bought an SLZB-06 mg26 and installed it on the first floor.

However, I quickly found out that HA can’t run two OTBR instances at the same time. I tried setting up a standalone OTBR Docker container, but couldn’t get it working via TCP instead of USB (seems this isn’t really intended — and the HA Add-on docs also don’t recommend using a TCP-based RCP).

So, I reversed the setup — used the PoE RCP as HA’s main RCP and planned to run the USB dongle in a separate container later. Unfortunately, this didn’t work either. With the latest SLZB firmware (20250703) and OTBR 2.14, it initially worked fine, but then the OTBR add-on started crashing randomly without the watchdog restarting it. The logs look like this:

[W] P-RadioSpinel-: radio tx timeout
[W] P-RadioSpinel-: RCP failure detected
[W] P-RadioSpinel-: Trying to recover (1/2)
...
[W] P-RadioSpinel-: Error processing result: NoBufs
[W] P-RadioSpinel-: Error waiting response: NoBufs
...
[C] Platform------: RestoreProperties() at radio_spinel.cpp:2218: Failure

So I went back to the initial setup — the Sonoff Dongle directly connected to Home Assistant, plus two additional Eve Smart Plugs that should, in theory, improve the mesh network.
That setup lasted not even a day. Now I’m stuck with a never-ending loop of:

00:44:44.899 [N] Mle-----------: Different partition (peer:272500625, local:1408724729)
00:44:44.899 [W] Mle-----------: Failed to process Advertisement: LinkMarginLow

I should also mention that there are three Amazon Echos in the house, running their own Thread network — which of course doesn’t integrate into HA’s Thread network. I’d prefer not to use the Amazon devices as the backbone unless that’s the only viable solution.

If anyone has run into similar issues or found a reliable configuration, I’d be very grateful for your insights or recommendations.

Thanks in advance!

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First you need to make sure you have used different frequencies for your WiFi, Zigbee, Thread and what else you may have running in the 2.4Ghz band.
You also need to take neighborhood usage into account.

Secondly you have very few devices in your Matter fabric.
My suggestion is to add more mains power devices and not just around the problematic devices, but also between and make a wide mesh between the TBR and the devices.
With radio signals the direct way is not always the best, so make other paths too.

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This is the correct way. Routing nodes will improve and extend the mesh far more efficiently and easily than adding border routers. In my opinion it’s worth figuring out why this option didn’t work for you.

Try moving one Eve plug closer to the TBR until you have a stable connection. Then move the second Eve plug within range of the first Eve plug. Hopefully by then your sensors will have a path to the TBR, although it’s unclear how long it will take the network to “settle” on the mesh paths (a day maybe?). You can make your own cheap Thread repeater using a usb-powered esp32-h2 dev board (using esphome) if more coverage is necessary.

It’s unfortunate that Amazon’s Thread implementation does not permit you to join them to your HA mesh (although the opposite works, but you’d have to re-pair everything). Your best hope with the Echos is that a future firmware update supports the new credential-sharing feature in Thread v1.4, but again, more TBRs isn’t always a good thing.

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Thanks for your comments. Got it.

The “Failed to process Advertisement: LinkMarginLow” showing up recently, was only to be solved, but unplugging the Eve Energy plugs. Don’t really understand the conflict there. I have removed the Zigbee Stick and all Thread capable Echos for the time being, but only the removal of the Eve plugs solved it. Resettet them and reconnected - so far all fine.

Will think about adding new devices, but tbh, there is not really much “Full Thread Devices”, i.e. pluged into power, which I could need. Can think of Nanoleef or Aquara Bulbs as a replacement for the few Hue ones I have.

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