I have no clue how mac's work these days, But in a windows environment I have 2-3 different IP addresses (and classes) bound to a single adapter. So I can have NDI, Artnet, Show Kontrol, and Novastar on the same adapter with 3-4 different IP addresses. A single Gigabit connection is more than enough for what I'm sending/receiving. Maybe mac's can do this too?????
Don't forget to set up your manual metric's when using multiple adapters otherwise NDI does whatever it wants and you may bet it coming through the wrong adapter.
I wish NDI would allow you to choose what adapter to use rather than having to change your NIC's metrics