Check the below:
1. If target device enable RDP permission for remote servers.
2. If there is firewall or antivirus to block the port, default is 3389 between target server and PAM.
3. Check DNS working well or not.
Below comes a KB talks about DNS cause for such issue.
Error on Access RDP Connections:
https://knowledge.broadcom.com/external/article/6551/error-on-access-rdp-connections.html