TMG 2010 SP1: Cannot publish a website through TMG server when using any port except port 80

Introduction Cannot create a weblistener using any port other then 80 for non-ssl website publishing or trying to modify WebListener settings via UI for non-ssl website publishing. For example trying to use port 8080 on the listener as the port number in front of non-ssl connection option it gives an error: Repro steps Create a…