Hello Josh Adcock,
Identify Remote Desktop Gateway server address and DNS name(s) the certificate secures: Click View Certificate -> Details -> Subject Alternative Name
Does certificate list DNS name that secures Remote Desktop Gateway server address?
Possible Solutions:
When incorrect RD Gateway server address was entered in RDP client:
Update RDP client connection to use server name that is secured by certificate, RDP client -> Advanced Tab -> click Settings under Connect from anywhere -> Use these RD Gateway server settings
Installed RD Gateway certificate does not secure RD Gateway server address:
Update RD Gateway certificate to use desired
RD Gateway Manager snap-in -> SSL Certificate tab -> Import a certificate into Personal Store -> Browse and Import Certificate
Note: If certificate does not show in list you must first import certificate .PFX into local computer
store.
Note: Also see domain - Name Mismatch - Incorrect Remote Computer Name - Server Fault because certificate must secure Remote Computer and RD Gateway
Additional resources:
- Certificate name mismatch on a RDS 2016 Farm - Microsoft Remote Desktop Services
- RDS Gateway / AD with .local suffix / Certificate Mismatch
- RDS Certificate Mismatch - Microsoft Remote Desktop Services
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