Hi,
Did you found information about how iptables rules are stored? Including the NAT. I have a similar problem, but the issue is that there is a bug that doesn’t allow me to disable NAT for any interface that was already configured for NAT, as soon as I press the button to exclude the interface, the button dissapears. So I’m planning to make the change directly on the configuration files, temporarely I erased the iptables line.
Regards,
Vianney