Some services in Debian/Ubuntu need to start after the Tailscale service is not only started/active, but has fully come up (in so much that it passes network traffic, which can take 5-10 seconds after the service starts). This is crucial when binding services solely to the Tailscale interface such that they require it to be fully operational before binding can successfully complete. Some services like the Zabbix agent may initially fail but will retry and start successfully once Tailscale is fully operational, but other services like netatalk (used for Apple file sharing) will generally fail to start or bind and will not reattempt, forcing a manual intervention of restarting that service.
To account for this, a "ExecStartPost" within the Tailscale systemd config monitors when the host can successfully ping 100.100.100.100 (the "localhost" IP within Tailscale) such that other services that depend on Tailscale won't attempt to start until the ping is successful. From there, the dependent services
