It sounds to me like the problem he encountered stems from a flawed understanding that IP:MAC:Machine has 1:1:1 relationship and that subnet:router:default-route:external-ip:machine has a 1:1:1:1:n relationship, which are only the cases for media consumption devices and cloud servers.

And so when he tried to work with a machine without exactly one(1) IP and one(1) active NIC going up the NAT router to the Internet it immediately failed. This is surprising to me that of MANGA, Google seems to be on the weak side with respect to IP networking.