NAT-PMP/PCP rules show ? for internal IP address

[axellarsson]

Since upgrading from 2025.07.1 to 2026.03, NAT-PMP/PCP is no longer working for me. In Status > UPnP IGD & PCP, I see port mappings being created by clients on the network with unique external port numbers and a common internal port number (41641 for Tailscale), but the Internal IP is shown with a ?.

I have tried restarting the tailscale clients on the network and the miniupnpd service, but the mappings continue to be created with an undetermined ? IP address.

Since I was using this primarily for Tailscale, I've since enabled the experimental Endpoint Independent Mapping for UDP, which is a better solution overall then relying on PCP and have been able to restore direct connections between Tailscale peers over IPv4. Nevertheless, wanted to check if anyone else is seeing the same behavior from NAT-PMP/PCP on the latest release.

[Bob.Dig]

I am not using it but a quick test confirms your findings.