Unable to add Meross Matter device to HA (using Thread Border Router)

Configuration Matter/Thread
1

Having an issue hooking up a Meross presence sensor (which runs Matter) to my Home Assistant install. Using the HA app on my phone to add it but it does not pass the ‘Checking connectivity to the Thread network…’ stage.

I’m running Proxmox with one LXC hosting Docker containers running HA, Matter-server and multipan (to use the Sonoff dongle with firmware for both Zigbee and Thread Border Router). HA is able to use some TP link Matter devices but these use the TP hub.
Zigbee using the dongle is working and there is a Thread Border Router up as well. This was detected by HA and added to HA.

On the LXC VM I have the following IPv6 settings:

net.ipv6.conf.eth0.accept_ra = 2
net.ipv6.conf.eth0.accept_ra_rt_info_max_plen = 64
net.ipv6.conf.eth0.forwarding = 1

On Proxmox server I have added

net.ipv6.conf.vmbr1.accept_ra=2
net.ipv6.conf.vmbr1.autoconf=1
net.ipv6.conf.vmbr1.forwarding=1

to the sysctl.conf

By the looks of it the LXC does receive an IPv6 address, starting with fd28:413d

From the log for the Matter server I see that the server initialized successfully but it does start with a Network is unreachable error.

2026-01-31 05:36:25.889 (Dummy-2) CHIP_ERROR [chip.native.DIS] Failed to advertise records: src/inet/UDPEndPointImplSockets.cpp:417: OS Error 0x02000065: Network is unreachable
2026-01-31 05:36:25.894 (Dummy-2) CHIP_ERROR [chip.native.DL] Long dispatch time: 284 ms, for event type 2
...
2026-01-31 05:36:27.246 (MainThread) INFO [matter_server.server.vendor_info] Saving vendor info to storage.
2026-01-31 05:36:27.251 (MainThread) INFO [matter_server.server.device_controller] Loaded 1 nodes from stored configuration
2026-01-31 05:36:27.256 (MainThread) INFO [matter_server.server.server] Matter Server successfully initialized.
2026-01-31 05:36:27.883 (MainThread) INFO [matter_server.server.device_controller.mdns] <Node:17> Discovered on mDNS
2026-01-31 05:36:27.883 (MainThread) INFO [matter_server.server.device_controller] <Node:17> Setting-up node...
2026-01-31 05:36:30.081 (MainThread) INFO [matter_server.server.device_controller] <Node:17> Setting up attributes and events subscription.
2026-01-31 05:36:30.248 (MainThread) INFO [matter_server.server.device_controller] <Node:17> Subscription succeeded with report interval [1, 60]

The multipan logs

otbr-agent[208]: 00:07:11.731 [N] MeshForwarder-: Failed to send IPv6 UDP msg, len:184, chksum:8d86, ecn:no, to:e2ce8ca3e34dc5e0, sec:yes, error:NoAck, prio:net
otbr-agent[208]: 00:07:11.731 [N] MeshForwarder-:     src:[fe80:0:0:0:185e:b2bb:3a97:bb70]:19788
otbr-agent[208]: 00:07:11.731 [N] MeshForwarder-:     dst:[fe80:0:0:0:e0ce:8ca3:e34d:c5e0]:19788
otbr-agent[208]: 00:07:31.722 [N] MeshForwarder-: Dropping (reassembly queue) IPv6 UDP msg, len:518, chksum:a1bf, ecn:no, sec:yes, error:ReassemblyTimeout, prio:normal, rss:-94.25
otbr-agent[208]: 00:07:31.722 [N] MeshForwarder-:     src:[fd28:413d:c16c:f212:1c3e:264f:2365:e3a9]:49154
otbr-agent[208]: 00:07:31.722 [N] MeshForwarder-:     dst:[fd28:413d:c16c:f212:643d:249a:90eb:7149]:53536
otbr-agent[208]: 00:25:12.497 [W] Mle-----------: Failed to process UDP: Duplicated
otbr-agent[208]: 00:25:12.509 [W] Mle-----------: Failed to process UDP: Duplicated
otbr-agent[208]: 00:25:12.515 [W] Mle-----------: Failed to process UDP: Duplicated
otbr-agent[208]: 00:25:12.521 [W] Mle-----------: Failed to process UDP: Duplicated
otbr-agent[208]: 00:25:26.527 [W] Platform------: Handle transmit done failed: ChannelAccessFailure
2

You have network configuration issues, probably subnetting.

3

As far as I know the Methods devices are WiFi based, so your OTBR have no influence on the issue here.
This is a Matter or WiFi issue.

Remember that you need IPv6 and VLANs will complicate things a lot.

4

ProxMox, VLANs, T-P Link, IPv6, Docker, VM - any other trigger keywords to make me run away and hide?
Best of luck. You have networking configuration issues is my educated guess.

5

I agree with IOT7712 and because your setup is not standardized then it is hard to say where the error is.
Luckily you can leave the Thread network and OTBR out, since it is probably a WiFi-based device.

6

This is a Matter over Thread device so I can’t leave any of that out.
Re this setup not being ‘standardised’…it is not uncommon either. All components involved do use the same network though (incl. the phone running the HA Companion app). Having IPv6 running is a requirement Matter over Thread.

7

Obviously, others have pointed out some things to look for that might be miss configured, but I’m also having issues with Meross devices, only Matter over Wifi. My set up is super vanilla - HA Green and Apple TV 4k. I can add 4 x smart sockets, 1 x presence sensor and 1 x garage door opener to a) the Meross app and b) HomeKit but nothing has worked to get them to show up in HA. I have Tapo and LiFX Matter devices that do show up so my issue seems to be Meross specific. Let us know if you work anything out please :slight_smile: