If a tailscale key has expired, the start script for the tailscale daemon will issue an authentication prompt and wait forever. This means that not all rc.conf scripts will run, including, most emphatically, the sshd start script (and, if installed, saltstack, which has a useful cmd.run backdoor :)) A console login is required to sort this, which may be inconvenient. Workarounds: 1) disable key expiry (not necessarily wise) 2) remove the tailscale stuff from rc.conf and create a startscript at the end of rc.local
*** This bug has been marked as a duplicate of bug 282690 ***