RDP Works PC to PC, but I get Error Code 0x204 MAC to PC

I found a solution for the issues I was facing.

Bought a new MacBook Air with Apple M1 chip and migrated the MacBook from old to new. VPN and Microsoft RDP worked flawlessly on my old Mac, but didn't work at the new MacBook; exact same settings for VPN and RDP.

I had my IT guy look at it and he found a solution:

in Mac > Settings > Network you see the circle with three dots in the bottom left > set order .... (I have Dutch language, so not sure what it is in English) and change the order to have VPN on top, above wifi/Lan.
This worked for me!

Unfortunately I continue to receive the 0x204 when attempting to RDP from my High Sierra MAc to my WIn10 Pro Desktop. Just to restate, I am able to RDP from my Win10 laptop to the Win10 Pro Desktop.

1. I did verify I the Uncheck "Allow connections only from computers running Remote Desktop with Network Level Authentication"
2. I confirmed the MAC firewall allows remote desktop connections
3. I verified port 3389 is open from the MAC side and that my router forwards to remote desktop to port 3389. The results of my MAC scan are below: Port Scan has started… Port Scanning host: 10.0.0.31

Open TCP Port: 3389 ms-wbt-server
Port Scan has completed…

4 I deleted UBF8T346G9.com.microsoft.rdc and restarted my MAC, it still didn't work.
5. I deleted and reinstalled the app, still same error 0x204

  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

I figured it out this morning. When entering the PC name in the Remote Desktop App on my MAC, it worked when inputting the IP Address of my Win10 Pro PC rather than the actual PC Name. For some reason, the App did not recognize the PC Name, even though i confirmed it was correct and added/re-added countless times.

Nevertheless, problem solved! Thanks for your suggestions.

Hi,

Error code 0x204 might be caused by serveral different reasons. So, you can try below methods to see if they help.

1. On the remote windows PC, open "Run" and input "SystemPropertiesRemote.exe" to open up the System Properties screen.
   Make sure you have checked "Allow remote connections to this computer", and uncheck "Allow connections only from computers running Remote Desktop with
   Network Level Authentication" if your MAC pc is on the different network from the windows pc.
2. Allow Remote Deskstop through Windows Firewall. From both sides, you must ensure the firewall allows the remote desktop connection. Since the windows PC canbe
   remoted from another windows PC. There should be no problem from the widnows side, you should check from the MAC side.
3. Ensure 3389 port is open from both sides. On your case, you should pay more attention to mac side. (Network Utility > Port Scan > Only test ports betwee 3389 and
   3389). Or maybe you need to also assure the router is configured to forward the remote desktop port 3389.
4. If all above methods do not help, remove the temp folder of Remote Dekstop for mac (close the remote desktop app > Finder > search "group containers" > delete
   UBF8T346G9.com.microsoft.rdc by right-clicking and choosing Move to bin from the context menu > restart your MAC pc)
5. The last method you can try is to reinstall the app or install the latest version of the microsoft remote desktop app for mac.
   https://apps.apple.com/us/app/microsoft-remote-desktop/id1295203466?mt=12

Thanks,

Eleven

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I am having the same problem. I running Mac OS11 (Big Sur) on a M1 Mac mini. I am using Sonicwall Mobile Connect to connect to make the VPN connection to my PC at work and that is working. However, when I connect with Microsoft Remote Desktop, I get the 0x204 error. I have unchecked "Use system proxy configuration" and also unchecked "Use hardware acceleration when possible".

I was unable to access the Group Containers or locate the UBF8T346G9.com.microsoft.rdc file. It appears that this has changed in OS11 Big Sur. Also, the Network Utility no longer exists so I am unable to verify the port. Apparently this can still be done through the Terminal, but I have no knowledge of how to do this.

I am able to VPN in and use Remote Desktop from my home on Windows PC to get into my work computer, so I know that the computer at work is set up correctly and that my router at home is not blocking the connection.