OnlineNIC Connection Errors

Problem

You see connection errors while using OnlineNIC for domain registrations.

For a list of error codes for the OnlineNIC API, see OnlineNIC Response Parameters.

Cause

This error indicates that your firewall is blocking the connection.

Solution

This troubleshooting information only applies to self-hosted WHMCS installations.

Check to ensure that port 20001 is open in your server’s firewall.

troubleshooting troubleshooting-article domain-registration onlinenic

Last modified: 2025 October 17