I have this done on my personal server. On the server itself, in iptables, I block access to port 80, and leave 443 open. Now on my router, I have both 80 and 443 blocked, and I enabled port forwarding for the port of my choice to port 443 on my server. Then in a web browser, you need to force https to use a different port as such:
https://www.examplehost.com:666