From Xojo Documentation
|This property is only available for Web applications.|
The port number that will be used to communicate securely with the web app.
SSL options are only valid for stand-alone web apps. The Certificate must be located next to the app and its name must match the app name. For example, if the web app is called "MyApp" then the certificate must be called "MyApp.crt".
If you are setting this in code, be sure to set it in the WebApplication.Open event handler.
The SSLPort value can also be set at launch time by appending the --secureport command line parameter.