TLDR: Modify your power plan to ensure your VM isn’t going to sleep!
I had recently deployed a new Windows 10 based VM that would serve as an RDP jump box to access lab resources. Initially RDP worked fine, but I noticed that after a while I couldn’t connect any more. The only way to rouse it from this state was to open a direct console window from the vSphere Client, or to reboot the VM.
The exact error message from the Remote Desktop for Mac window is:
“We couldn’t connect to the remote PC. Make sure the PC is turned on and connected to the network, and that remote access is enabled.
Error code: 0x204”
In addition to the 0x204 error, I also saw “Error code: 0x4” numerous times as well.
The two error codes I kept getting (0x204 and 0x4) were not helpful and just led me on a wild goose chase. These codes were only reported on the Mac RDP client and Windows was more generic:
Clearly the message “Make sure the PC is turned on” garnered no attention from a seasoned IT professional like me, but in the end turned out to be relevant. The issue was that the Windows 10 VM was going to sleep.
I only noticed this when I saw a blacked-out screen in the console preview and the lack of a hostname or IP address listed. This tells me that VMware tools hasn’t checked in for a period of time.
I’m not sure if an incoming RDP connection attempt would wake a physical machine in this state, but sleep isn’t very beneficial to a VM. I simply modified the power settings to prevent sleep and hibernation and the issue hasn’t happened again.
Windows Server varieties don’t behave this way, but because Windows 10 is primarily intended for bare-metal laptop and desktop use cases, power saving features are enabled by default.
This is a pretty basic problem, but I thought I’d do a post just in case it helps someone else who overlooked the obvious like I did and instead tried chasing up hexadecimal error codes 🙂
vswitchzero 
Thank you! Had issue with this.