Why doesn't it save the rules in iptables?

Question

ubuntu

installed Ubuntu Server 18.04 configured and registered rules in iptables and everything works fine until reboot
tried to install sudo apt-get install iptables-persistent
after installation it says whether to save the rules in /etc/iptables/rules.v4 I write yes, I check that the rules are there really registered,
nothing happens when you reboot
The rules there refer to the Nata table The
question is, why can not save the rules and what other options are there for saving the rules?

Answer 1

Because it worked at 16, and at 18 you need to install 2 packages
Everything else is +/- as well.

Answer 2

Because the default in 18.04 is ufw.

Answer 3

sudo /etc/init.d/iptables-persistent save
sudo /etc/init.d/iptables-persistent reload

Answer 4

As a result, I solved the problem like this, I had Webmin installed and there I registered the rules for the Firewall in the admin panel and everything worked, I don’t know why (but the main thing works.