DMZ

https://searchsecurity.techtarget.com/definition/DMZ

a DMZ (demilitarized zone), also sometimes known as a perimeter network or a screened subnetwork, is a physical or logical subnet that separates an internal local area network (LAN) from other untrusted networks -- usually the internet. External-facing servers, resources and services are located in the DMZ. Therefore, they are accessible from the internet, but the rest of the internal LAN remains unreachable. This provides an additional layer of security to the LAN as it restricts a hacker's ability to directly access internal servers and data via the internet.