Hey MichaIng, thanks you were right about the shutdown command!
Just out of curiosity I still tested with shutdown -r, the result was:
Failed to connect to bus: No such file or directory
And the result with reboot is
/bin/sh: 1: reboot: not found
Is it because the cron is ran as root and it should be as the user dietpi instead? Because I found this:
I’ll wait for an answer here before just dumping /usr/sbin/reboot, in case there is a more “proper” way of doing this (And also so I can mark the next post as the official solution for anyone ending up here from Google).