Based on your farm configuration, the Farm Controller will automatically change its own Web Portal settings to become a Gateway Server, allowing users connecting from the TSplus Web Portal of the Farm Controller, not to connect directly to the Farm Controller itself, but to one of the application server of the Farm.
However, if you want to manually change this behaviour, you can do so by clicking on the "WEB" tile, then on the Web Portal Preferences button.
Click on "Save" to save this setting.