Apple TV 4K: Thread/Matter fail with NordVPN on Ethernet

Apple TV 4K 3rd gen Home hub: Thread/Matter devices go No Response with NordVPN on Ethernet, stable on Wi-Fi

I had persistent Thread/Matter instability in Apple Home using an Apple TV as the only Home hub/border router. My Thread/Matter devices (Eve Door/Window sensors, Matter over Thread) would all go No Response together. Sometimes they would appear online but door events would not register and automations/notifications would not run. Apple TV still showed as the Connected Home hub.

What fixed it was isolating the Apple TV VPN and network interface. I was running NordVPN on the Apple TV. With NordVPN enabled and the Apple TV connected by Ethernet, the Thread/Matter network would flap and devices would fail. Turning NordVPN off restored everything immediately. Keeping NordVPN on but switching the Apple TV from Ethernet to Wi-Fi (same LAN) made the system stable, and I have not been able to reproduce the Thread/Matter dropouts since.

If anyone is seeing Matter/Thread devices fail after Apple TV restarts or randomly go No Response, and you run a VPN on the Apple TV, try disabling the VPN or switching Apple TV from Ethernet to Wi-Fi. It looks like the VPN may interfere with local network traffic needed for Home/Thread on Ethernet.

Setup: Apple TV 4K 3rd gen 128GB (Thread capable), tvOS 26.1/26.2, TP-Link Archer AXE75 with TP-Link RE450 extenders (OneMesh), Eve Door/Window sensors (Matter over Thread).

What I can reproduce consistently:

1. Apple TV on Ethernet with NordVPN enabled: Thread/Matter stability is poor (dropouts, automations stop).
2. Turning NordVPN off (still on Ethernet) restores the Thread/Matter devices quickly.
3. Keeping NordVPN enabled but switching Apple TV from Ethernet to Wi-Fi (same LAN) results in stable operation; I have not been able to reproduce the dropouts in this configuration so far.

Why I am unsure who is at fault:

• It might be a NordVPN limitation/bug on tvOS, especially around local network traffic, multicast, or Bonjour/mDNS on Ethernet.
• It might be a tvOS/Home/Thread bug that NordVPN triggers or worsens.
• The key is that the behavior changes based on Apple TV network interface (Ethernet vs Wi-Fi) while using the same VPN.

Questions:

• Has anyone else seen Thread/Matter devices fail specifically when Apple TV is on Ethernet with a VPN enabled?
• Is there a known tvOS/Home bug in 26.1/26.2 that affects Thread border router behavior?
• Are there recommended settings to ensure local network traffic (mDNS/Bonjour/multicast) is not impacted when a VPN is used on Apple TV?

Workaround that works for me right now: keep NordVPN enabled but use Apple TV on Wi-Fi instead of Ethernet.