https://bozza.ru/art-259.html
1. Disable the Firewall: To disable firewalld service please run the following command.
sudo systemctl disable firewalld

2. Enable the Firewall: If you want to enable the service please run the command.
systemctl enable

3. Stop the Firewall: You can also deactivate the service using the following command
systemctl stop firewalld

4. Start the Firewall: To activate the command run
systemctl start firewalld

работает ли фаервол
firewall-cmd —state

смотрим что разрешено
firewall-cmd —permanent —list-all

Убираем разрешающее правило для ip6:
firewall-cmd —permanent —zone=public —remove-service=dhcpv6-client

Разрешим соединение на порт 2234/tcp:
firewall-cmd —permanent —zone=public —add-port=2234/tcp

Перезагрузим правила:
firewall-cmd —reload

Ещё примеры:
firewall-cmd —permanent —zone=public —remove-service=dhcpv6-client
firewall-cmd —permanent —zone=public —remove-service=mysql
firewall-cmd —permanent —zone=public —remove-port=80/tcp
firewall-cmd —permanent —zone=public —add-service=http
firewall-cmd —permanent —zone=public —add-port=3306/tcp