Introduction: The Sudden Wall of Connectivity
On the remote Windows machine (Server or Pro): Remote Desktop Connection Error Code 0x904 Extended Error
Action: Try establishing the connection using the server’s static IP address rather than its Friendly Domain Name (FQDN). Logs and advanced diagnostics
2. Adjust the RD Gateway Settings If you are connecting through an RD Gateway: Test with Network Level Authentication (NLA)
Action: Use the Group Policy Editor (gpedit.msc) on the server. Navigate to Computer Configuration > Admin Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Security.
On the host machine, ensure Remote Desktop and Remote Desktop (WebSocket) are allowed for both Public and Private networks in the Windows Firewall.
Restart the Remote Desktop Services (as shown in Quick Fixes) to force Windows to generate a new valid certificate. 2. Adjust Security Layer Settings (GPO)