Hotspot port number

Hello guys
I want to forward WAN ip (public ip address) to hotspot ip (private ip address)
I tried to forward from wan to hotspot but i dont know what port number to use for hotspot !
Any help about this problem?!
Thanks alot

It is not clear, for me, what you want.
The purpose of hotspot is to catch connections generated in your lan and forward them to a hotspot login page to force users authentificate themselfs. Why would you do that from wan?

Thanks for reply
I want to authenticate users who access my web server from WAN

This usualy is done with htaccess in your web server configuration, directly on webserver