cron job reconnect PPPoE

[a-kempka]

How do cron jobs work that are executed at a specific time and not after booting up the UDMP?

I'd like to set up a PPPoE reconnect at 3am that persists thorughout reboots and firmware updates:
0 3 * * * root /usr/bin/killall -HUP pppd

Would putting the above command it in /mnt/data/on_boot.sh/reconnect.sh (in an executable script with #!/bin/sh, of course) spawn a new cron job after each reboot so that it gets dublicated every time the UDMP reboots?
What are the rules for the numbered prefixes in /mnt/data/on_boot.d/? (would this mean the file should be named 10-reconnect.sh?

[ilkertanli]

Save below script under /mnt/data/on_boot.d/ and change the reboot command with whatever you want to do (killall -HUP pppd). Script checks the date when it matches to a specified time 05:00:00 it executes.

#!/bin/sh
while true;
do
DATE=date | cut -d' ' -f4
if [[ $DATE == "05:00:00" ]]
then
reboot
sleep 30s
fi
done