I have deployed an RDS server on Windows 2016 Standard with all the roles: RD Web Access, RD Gateway, RD Licensing, RD Connection Broker and RD Session Host. I have installed a wildcard certificate on the IIS (with https binding) and assigned it to all RDS services, including the RD Gateway, and the certificate status is "Trusted" and "Ok".
All published apps are working fine from the internal network. As for the external (internet) access, I'm able to sign in to the portal and see all the resources, but whenever I click on any of them I have a popup message from "RD Gateway Server Credentials" asking for user and password. I'm supplying the correct credentials yet I'm faced with "Your computer can't connect to the remote computer because the Remote Desktop Gateway server is temporarily unavailable..."
Note the following details:
The local domain is different than the external one, and the wildcard certificate was created for the public one.
RD Gateway in the deployment properties was configured to use the external FQDN (matching the certificate).
Only Port 443 is published on the internet.
All clients are using Windows 10 (Pro/Ent).
Any help would be much appreciated! Been working days to solve this issue and read many articles but couldn't find the proper solution.