Thank you! After going through the “trouble” of reading a few docker basics , I found that docker start / docker stop commands work fine when I call them from the shell.
I have then put the start / stop commands in shell script files (and marked them as executable, same as with the Dragonfish version). When I tried to run these scrips from a Cron Job, I always got an “unexpected status 0x57f”. However, when I put the docker start / docker stop commands directly in the command field of the Cron Job, it works fine (and that’s good enough for me).