There are several steps you can take to diagnose forwarding errors on multiple NNTP servers:
1. Check the configuration settings on each server to ensure that forwarding is enabled and properly configured.
1. Use diagnostic tools such as traceroute or ping to verify that the servers are properly connected and communicating with each other.
1. Monitor the NNTP logs for any errors or warnings related to forwarding. Look for error messages that indicate problems with connecting to the destination server or problems with authentication.
1. Verify that the destination server is properly configured to accept incoming messages and that the forwarding address is correctly specified.
1. Check for any network or firewall issues that may be blocking the forwarding connection.
1. If you are still unable to resolve the issue, consider consulting with a qualified NNTP server administrator or support team. They can help you troubleshoot the problem and provide advice on how to resolve it.
