I’ve had a few Matter over Thread devices for a while, and recently I significantly expanded my network thanks to the new IKEA devices. I’ve been using the new OHF Matter(.js) Server available as an option in the current Matter Server App, along with the OpenThread Border Router App. Things were very good (the new Matter server is looking great!), but I was still running into frustrating issues where Thread devices would just go offline for a while with no seeming rhyme or reason.
I tried moving devices around, re-commissioning problematic devices, reviewing my UniFi configuration to ensure that things were configured the right way, and none of it seemed to actually do any good.
What seems to have done the trick for me was looking a bit more into how running HA inside of Proxmox VE impacts things. By default, VMs are connected to my physical network via a Linux bridge, essentially a virtual switch, usually vmbr0. Just like any of your physical network infrastructure, there are options and features here that can impact how network services traverse the interface.
The tweak I made was to disable IGMP/MLD snooping on the bridge interface. You can test this out from the Proxmox host shell:
echo 0 > /sys/class/net/vmbr0/bridge/multicast_snooping
You can make this setting persist by editing /etc/network/interfaces on the host as well:
auto vmbr0
iface vmbr0 inet static
address 192.168.1.10/24
gateway 192.168.1.1
bridge-ports eno1
bridge-stp off
bridge-fd 0
bridge-mcsnoop no <-- Add this line
Your mileage may vary but for me this was the difference between a mostly-working (which means completely untrustworthy) Thread network to a functional, responsive, and most importantly reliable Thread network.
I’ll be curious to hear if this helps anyone else. I waited a few days before posting to see if any ghosts or gremlins popped up but so far I’ve had nothing but smooth sailing since making the change.
