How to use journalctl and dependency order to troubleshoot slow systemd service startup

There is an internal service that takes two or three minutes to restart. Business colleagues only see that the page won't open, and the on-duty staff keeps running systemctl restart, but it's slow every time. The service itself doesn't start slowly; the slowness is caused by systemd waiting for a network mount. When troubleshooting, I first check systemctl status and journalctl -u service -b to…