Ok I see thats fine and should work now without me doing anything.
What about is there a way to.... when a visitor goes to https://portal.xx.co.uk
(without specifying port) and when it gets to my server it gets diverted to port 81 and so gets to the ISPConfig pages.
If you see what I am getting at I want to make it easier for users to get to the portal without knowing port numbers.
I could just put a link on my main home page and the link has got the web address and port number.