With a dedicated certificate, the settings you posted should work just fine.
If you're getting "connection refused" messages, those are coming from the webserver ... which means you'll need to talk to the server administrator to fix that. You'd likely get the very same error trying to access a plain .html file instead of the index.php that runs Zen Cart ... meaning the issue has nothing to do with Zen Cart. The refusal is happening before it even gets to Zen Cart.