Remote Desktop Services (formerly known as Terminal Services) accelerates and extends desktop and application deployments to any device. Remote Desktop Services improves remote worker efficiency, while helping to keep critical intellectual property secure and simplifies regulatory compliance. Enable virtual desktop infrastructure (VDI), session-based desktops, and applications, and allow users to work anywhere. Remote Desktop Services provides three deployment choices, allowing flexibility to deploy the right type of VDI desktop for users, all from a single platform. Host either sessions-based desktop, pooled virtual machines, or personal virtual machines. This External Connector permits multiple external users to access a single Remote Desktop server. If you have multiple servers, you need multiple external connectors in addition to any required Windows Server External Connectors.

Windows Server 2025 Remote Desktop Services External Connector provides license for unlimited number of external users connecting to internal terminal server. 

The Windows Server 2025 Remote Desktop Services (RDS) External Connector is essential for several reasons, especially when dealing with external users who need to access your server:

Access for External Users: The External Connector license allows external users (non-employees) to access your server without needing individual RDS CALs. This is particularly useful for organizations that provide services to clients, partners, or contractors.
 
Cost Efficiency: Instead of purchasing individual RDS CALs for each external user, the External Connector license provides a more cost-effective solution. This can significantly reduce licensing costs when dealing with a large number of external users.
 
Simplified Licensing Management: Managing licenses for a large number of external users can be complex. The External Connector simplifies this by providing a single license that covers all external users, making it easier to stay compliant and manage access.

Compliance and Legal Requirements: Microsoft’s licensing terms require that every user or device accessing the server via RDS must have a corresponding CAL. The External Connector ensures that your organization remains compliant with these requirements when external users are involved
 
Enhanced Security and Control: By using the External Connector, you can better manage and secure access for external users. This helps maintain the integrity and security of your server environment while providing necessary access to external parties.

In summary, the RDS External Connector is crucial for providing cost-effective, compliant, and secure access to your server for external users, simplifying license management and ensuring that your organization meets all licensing requirements.