Windows Defender or third-party antivirus software (like Bitdefender) blocking mstsc.exe or RDP traffic.
Ensure both and Remote Desktop (WebSocket) are checked for Private and Public networks.
The self-signed certificate used by Remote Desktop Services has expired and failed to renew automatically.
Search for in the Start menu. Click Change settings .
This is particularly common on Azure VMs where the MachineKeys folder becomes corrupt, preventing new certificate generation. Step-by-Step Solutions 1. Renew Expired RDP Certificates
If you can connect to some servers but not others on the same network, an expired certificate is the most likely culprit.
Enable and set it to RDP .