An alternative way of enabling the exit node mode without editing the start script or running frequent cron commands.
- Go to Lucy then System->Startup->Local startup
- Enter above the exit 0line:
( sleep 60; tailscale set --advertise-exit-node ) &
This will allow the router to start all processes, including Tailscale connection and, after 60s, will set the flag --advertise-exit-node.
This solution persists after the router updates.