Editing to NetworkInterfaces.plist for changing the network to en0.

Hi. I'm running Sierra 10.12.6. I want to get my iMessage and FaceTime running. I've got the valid (read "invalid") Serial Number, Board Serial Number, SmUUID etc. When I reboot and try to sign in (Should put it out there that I don't own an iOS device, so I don't have an existing iMessages / FaceTime account), I get an "error during activation. Please try again" message. I don't get a customer code, so that's good. It's probably because I use a USB WiFi Adapter, which shows up as en1 in my network lists.

I've tried deleting the preferences.plist and NetworkInterfaces.plist, but nothing. I still get my USB WiFi as en1.

So, I'm thinking about editing the NetworkInterfaces.plist myself. Can somebody tell me the right way to do that?