If you get the error " Connection has been closed. Another user may have logged in on the remote windows machine" while doing RDP into the remote windows server, then 'right click'->'inspect'-> click Console tab as show in the image below.
1. In order to overcome the error " NODE_RDP_PROTOCOL_X224_NEG_FAILURE()", ensure that Network Level Authentication is disabled for RDP under Control Panel->System->Remote settings
2. Also make sure to force TLS encryption on all RDP connections.
A. Run mmc in the Run application of your windows server. In the console, open File > Add/Remove Snap in > Select Global Policy Editor and add the selected Snap in .
B. Select Local Computer and then select Finish>OK
C.In the sidebar Navigate to Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Hosts > Security.Then Edit the "Require use of specific security layer for remote (RDP) connections" policy as shown below.
You need to select the security layer as SSL (TLS 1.0)