Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft which provides a user with a graphical interface to connect to another computer over a network connection. You will receive the following error “Your session has ended because of an error: Error Code 0x4″ whenever your Mac goes to sleep”. Below are some troubleshooting guides relating to RDP “We could not connect to the remote PC with error code 0x204 and make sure the PC is turned on and connected to the network–Part 1” and We could not connect to the remote PC with error code 0x204 and make sure the PC is turned on and connected to the network–Part 2.
Since this is actually not a problem, please use the following steps below to mitigate this issue. 
Solutions: Kindly refer to the steps below to resolve these issues.
1: Launch a new RDP connection or
2: Simply increase the maximum outstanding connections limit on the windows client machine. The following DWORD registry key controls this value.
See the following hyperlinks for what is Registry Editor and how to access the registry hives and how to search through Windows Registry.
-Launch the Windows registry, navigate through hives to troubleshoot the 0x4 Session Disconnection Error, as described below.
Computer\HKEY_LOCAL_MACHINE
- SYSTEM
- CurrentControlSet
- Control
- Terminal Server
- MaxOutstandingConnections
Now create the DWORD key if your machine doesn't have it.
- Set it to 10,000 (hex value)I hope you found this blog post about the 0x4 Session Disconnection Error helpful. Please let me know in the comment session if you have any questions.
