Port mismatch:443 error on the Gateway.
The following services could start listening port 443 before RAS SecureClientGateway service:
- Web Deployment Agent Service
- SQL Server Reporting services
- World Wide Web Publishing service
- IIS Admin Service
- RD Gateway Service
- KDC Proxy Server Service (KPS) is enabled.
Stop the service that is listening port 443 if it is not needed or change its configuration to listen a different port, so that RAS Gateway could listen port 443.
Change RAS Gateway port for TLS/SSL connections from 443 to some other available port.