I used this version  Armbian 23.02.0-trunk Bullseye with Linux 5.15.90-flippy-81+o.
 
	I solved the crontab problem by this way.
 
	1. create a file under the folder /etc/cron.d/ , such as [ vi /etc/cron.d/rebootvms ]
 
	2. write the crontab job, such as [ 1 1 * * *   root    /usr/sbin/reboot ]
 
	3. restart the crontab service, [  service crontab restart ]
 
	done!