How to find a device on the local network from MacOS and find out its ip outside the mask?

Question

Network administration

The device may not respond to pings, but some port is definitely open.

Answer 1

For starters, it's quite possible that data transfer between your subnet and the one where the target device is located is prohibited on the firewall/router. In this case, an open port will not do anything - just like ping, the packet simply will not reach.
If there are no restrictions on the router and you know the range of addresses for sure, you can try to scan it completely with something like nmap`a. In this case, the open port will help you determine the device address.

Answer 2

Behind the masks? No way.