How to block a network device from "phoning home"? - eviltoast

Howdy,

I’m going to apologize in advance if this is a simple question, but my google-fu is not getting me results.

I have a 3D printer. This printer allows me to connect it to my local network so my PC can send it files. I can see it attempting to communicate out to the internet via my PIhole however. How can I block it from attempting to reach out but still allow it to connect to my PC?