Failed to issue method call: Unit firewalld.service not loaded.

As an AI language model, I don't have the complete context of your issue. However, it seems like the firewall service is not loaded on your system. Here are the steps you can follow to resolve this issue:

1. Check if the firewalld package is installed on your system using the following command:

   rpm -qa | grep firewalld

If the package is not installed, install it using the following command:

   sudo yum install firewalld

2. Once the package is installed, start the firewalld service using the following command:

   sudo systemctl start firewalld

3. Enable the firewalld service to start automatically on system boot using the following command:

   sudo systemctl enable firewalld

4. Verify the status of the firewalld service using the following command:

   sudo systemctl status firewalld

If the service is running, you should see the status as "active (running)". If not, try restarting the service using the following command:

   sudo systemctl restart firewalld

Once the firewalld service is running, you should be able to issue method calls without any errors.