How many active users can log in to a Windows Server using RDP

By default, Windows Server allows 2 concurrent RDP sessions for administrative purposes. This applies to standard Remote Desktop for Administration and does not require RDS licensing.

If you need more than 2 simultaneous users, you must deploy Remote Desktop Services (RDS), install the RD Session Host role, and license the environment with the appropriate RDS CALs. Simply changing Group Policy settings does not remove the built-in 2-session limit.

So the short answer is: 2 concurrent RDP users by default; more than 2 requires a properly configured RDS deployment and RDS licensing.