Port mismatch:443 error on the Gateway.
Stopping the HTTP Service and dependent services does not help.
IIS is not installed or does not have a binding for port 443 configured.
Stopping the following services does not help:
- 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 KDC Proxy Server Service or change that port listened by RAS Secure Client Gateway from 443 to some other if stopping the service is not an option.
Described here in details: