What is the issue?

When a tailscale docker instance is advertised as an exit node, upon restarting that container by any means (recreate, system reboot), the "machines" panel will show a warning saying that "This machine has IP forwarding disabled and cannot relay traffic. Please enable IP forwarding on this machine." even though everything is still working correctly.

Steps to reproduce

1. Create a tailscale docker instance with ipv4_forwarding=1 and --advertise-exit-node
2. Authenticate node via tailscale.com admin page
3. Allow the node to act as exit node
4. Restart docker container or reboot host
5. Warning appears

Are there any recent changes that introduced the issue?

No response

OS

Linux

OS version

Ubuntu 24.04.1 (6.8.0-51)

Tailscale version

1.78.1

Other software

• UFW (dmesg doesn't show any TS traffic being blocked )

Bug report

No response