Here’s a small project to demonstrate Network Interfaces:
Here I have 0 interface, so the PopupMenu have only one entry in my MacBok Pro / El Capitan.
I am a bit surprised, and so my question is: is it the same for you with your Macintosh ?
BTW: the code comes from the LR, I add an interface as described in the LR (excepted the Open PushButton, added for the case internet was not set at application (project) run; you have time to activate internet and click in Scan to populate the PopupMenu with Network Interfaces.
How many Network Interfaces do you have ?