IPTables Not Working Error After Restarting the Server

If IPTables does not work after restarting the server, the error will be fixed if we save the iptables conditions and run it at startup.

#!/usr/bin/env bash

#### save iptables conditions and run at startup
apt update; apt upgrade -y; apt install -y iptables-persistent
iptables-save > /etc/iptables/rules.v4