I wanted to share my success story in getting some TP-Link Tapo plugs discovered through Matter. No matter what I tried, I couldn’t get the plugs adopted in Home Assistant nor Google Home. I then found the solution on YouTube!
YouTube creator Eric Welander gave me the solution in his “BEFORE getting Matter devices” video that IPV6 needs to be enabled on your network to allow Matter devices to get a required IPV6 address!!! I had disabled IPV6 on my OPNsense firewall across all networks and the WAN. Nobody mentions enabling IPV6 for Matter and I never saw it mentioned in the HA docs! Once enabled and configured, the plugs were instantly found and adopted!
I just wanted to share the solution in case anybody else is having adoption issues.