I am running TeamCity product at home for my development work and would like to publish the site via my Sophos XG Firewall. TeamCity runs on the internal domain namespace and to publish it to the Internet, you need to configure it so that it recognises the external domain namespace.
I don't want to make any change on the TeamCity, and luckily Sophos can do it !
Create Business Application Rule on your Sophos Firewall make sure the "Rewrite HTML" is selected as shown below. That's it!