Enable multiple RDP sessions on Windows Server 2012 &/or Higher

Step 1: Win + R on your server, on the pop up screen, type in gpedit.msc and click ok

Step 2: From the opened window after running the command, navigate to Computer Configuration>>Administrative Templates>>Windows Components>>Remote Desktop Services>>Remote Desktop Session Host>>Connections

Step 3: Select limit number of connections(Specifies whether Remote Desktop Services limits the number of simultaneous connections to the server.) right click on the selected option to edit the file. Changing the mode from not configured to enabled, under RD Maximum Connections allowed input the number of connections to be allowed i.e. 5 will only allow 5 connections to the server at the same time 999999 will allow unlimited connections. After configuration click on apply option then OK

To allow same user with multiple connections

This option comes in handy, lets say user Administrator is the only user on the host server, user A,B,C,D&E both want to connect to the server using username Administrator with the same credentials without kicking each other session host and establishing their unique sessions on host.

Step 1: Windows key + R to open run and type in regedit

Step 2: Navigate to Computer>>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server

Step 3: Select the highlighted option on the snippet above fSingleSessionPerUser, right click on it and select modify option, in the Value data field change the value to 0.(Zero means it does not limit concurrent connections by the same user)Press ok to set value. Note if value is set to Zero(0). You can ignore by hitting cancel