openssl s_client -connect <server_ip>:3389 -showcerts
Error 0x904 is purely a certificate trust mismatch . It is not a bug but a security feature preventing you from connecting to a server whose identity cannot be verified. The correct fix is to install a trusted certificate on the RDP server matching the connection hostname. i remote desktop connection error code 0x904 better
Scroll down to find and Remote Desktop Services UserMode Port Redirector . Right-click each service and select Properties . Change the Startup type to Automatic . If the service status is stopped, click Start . Click Apply and OK . openssl s_client -connect <