The is a common Windows Remote Desktop Protocol (RDP) failure that occurs when a connection is dropped or blocked immediately after entering credentials. It explicitly indicates a handshake breakdown or transport layer interruption, often tied to expired self-signed certificates, network instability, Network Level Authentication (NLA) mismatches, or third-party security software blocks .
Press Win + R , type mmc , and hit to open the Microsoft Management Console.
Following these steps in chronological order will systematically eliminate the certificate, permission, and network layer problems causing your Remote Desktop infrastructure to experience Error 0x904.
Enable Public/Private exceptions for Remote Desktop in Control Panel. Gateway Bug The is a common Windows Remote Desktop Protocol
is a critical network and security interruption that completely blocks your Remote Desktop Protocol (RDP) session. This specific combination indicates that while the client located the remote machine, the connection dropped during the initial handshake. The primary causes are unstable network pipelines, VPN packet drops, or TLS certificate private key access restrictions .
Open an elevated Command Prompt and restart the remote desktop services to force token regeneration: net stop termservice /y net start termservice Use code with caution. 2. Clear Third-Party Security App Blocks
An identified bug where the native client drops connections made via hostnames rather than raw IP addresses. Comprehensive Troubleshooting Matrix This specific combination indicates that while the client
If the issue persists, manually add C:\Windows\System32\mstsc.exe to the allowed list. 3. Adjust Security and Encryption Layers
Here is a summary of the best troubleshooting steps compiled from expert blog posts and technical forums: 1. Fix Expired RDP Certificates (Most Common Solution)
netsh interface ipv4 set subinterface "Your-Adapter-Name" mtu=1350 store=persistent Use code with caution. 4. Enable the RDGClientTransport Registry Key VPN packet drops
If this resolves the issue, add an exemption for mstsc.exe (remote desktop client) or create a firewall rule allowing port 3389. 4. Enable Specific Security Layer (RDP)
In 9 out of 10 cases, this resolves the issue immediately. Windows saves thumbnails and security data for each RDP connection.