Tag - Thread Border Router
A Thread Border Router topology for Home Assistant should start with one manageable preferred Thread network, known credentials, reachable Matter Server, IPv6/mDNS, and a clear local network boundary. More border routers help only after that boundary is stable.
Matter over Thread failures in Home Assistant are usually not caused by a broken device. They often come from a broken path between the phone, Matter Server, Thread Border Router, IPv6/mDNS discovery, Thread credentials, and the final Matter fabric.