Information
IPtables is an application that allows a system administrator to configure the IPv4 and IPv6 tables, chains and rules provided by the Linux kernel firewall.
IPtables is installed as a dependency with firewalld.
Rationale:
Running firewalld and IPtables concurrently may lead to conflict, therefore IPtables should be stopped and masked when using firewalld.
Solution
Run the following command to stop and mask iptables
systemctl --now mask iptables