This feature is new; it was added at the same time as the pre-set "Internet" definition that's bound to interfaces with a default gateway. I suppose they had to add the functionality to enable the creation of "Internet" and it was easy to adjust the Host/Network defintion routine. As BrucekConvergent observed above, it is helpful in the hands of someone that knows a lot. I wouldn't use it unless an Astaro engineer or developer tells you to do so.
Cheers - Bob
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005