Hello John,
To troubleshoot this issue, you can try the following steps:
1.Confirm that the RD Web Access website is correctly bound to the appropriate IP address and port.
2.Are there any specific error messages in the event log that could provide more information about the issue?
Making Sense of RDP Connection Event Logs
Note: Since the websites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.
3.Ensure that the SSL certificate used by the RD Web Access site is valid and properly configured. You can check the certificate bindings in IIS.
Regards,
Karlie