Android 'Cast Screen' Port

Hi All,

Trying to cast Android Screen via WIFI to Reflector within a school.

When selecting 'Cast Screen' no devices are shown, I suspect down to a Firewall issue.

Does anyone here know what Port 'Cast Screen' would use? Or how I would find this out?

I've tried using 'OS Monitor' on the Android device, but as 'Cast Screen' is shown as settings, I'm getting a very long list of potential suspects...

Many Thanks in advance,

Rowan.