How to run .sh script (iptables commands) on start up

I am using LineageOS 18.1

When I was on LOS 16, I used to edit the file /system/etc/init.d/00banner and put my iptables commands there, e.g.:

#!/system/bin/sh

sh -c 'iptables -A OUTPUT -m owner --uid-owner 10195 -d 203.205.255.78/23 -j REJECT'

All iptables commands I put in there used to run on phone start up. But in LOS 18.1, the /system/etc/init.d/ directory was deprecated.

1. I created and filled the custom script with the iptables commands above:

touch /system/etc/custominit.sh

chmod 0755 /system/etc/custominit.sh

2. Then I edited /system/etc/init/hw/init.rc and I added to the end:

chmod 0755 /system/etc/custominit

exec /system/etc/custominit

3. I also tried adding:

service custominit /system/bin/custominit.sh


 disabled


 oneshot

But none of this worked.

What is it that I doing wrong? I have root access but I do not want to install any additional apps on my phone for this, as it was possible to do on LOS 16.