Port forwarding Max router

[mbarnes]

So i know you do this on the mysky app but I need to set port 8123 to 443 for home assistant.

On my BT router you chose 8123 and pointed it to 443.

How do i do this on sky max router, surely just adding port 8123 to the rules isnt enough?

[mbarnes]

Same to allow Plex access from outside of my network. The guide says

"If you are manually forwarding a port, set that forward up beforehand and make sure you know the external port number which you are forwarding (remember that you need to forward the external port you choose to internal port 32400 for the internal IP address of the device running Plex Media Server)"

how can I actually forward a port not just open it?