I'd start by looking at the systemd unit files in /etc/systemd/system. Beware of service wants. I had straight up errors in a network unit file that caused wei

I'd start by looking at the systemd unit files in /etc/systemd/system. Beware of service wants. I had straight up errors in a network unit file that caused weird behavior (IP address disappearing). This was a long time ago though. Sometimes moving a unit from one target (graphical) to an earlier (multiuser) solves the issue. You might also have "defaults" in /usr/lib/systemd/ to compare with. systemctl and friends are really good tools for troubleshooting but takes a little while to get used to. Duck duck go is your friend. Finally, some volume technologies like VDO requires a x-systemd.requires statement in fstab.