Aary

Nice dual display setup :)

«I load ip_tables with modprobe, only to lose it after a reboot»

Write the module name into:
/etc/modules-load.d/<name>.conf — on most modern systemd distributions (Ubuntu, Arch, Fedora, etc.)
or /etc/modules on Debian-style systems.

OpenRC’s modules-load service reads configuration files from the following locations, in order of precedence
/usr/lib/modules-load.d/
/run/modules-load.d/
/etc/modules-load.d/

echo “ip_tables” >/etc/modules-load.d/ip_tables.conf