Having the same problem. It used to just plug right into my old Macbook. Firewire DOES not work with an adapter. You have to get a duo cable. One with 800 on one side and 1394 on the other. There is also a 1394b. My Belkin hub is working with my new iMac with a thunderbolt 3 to 1 adapter. The new iMac can also be used with all usb cables. I am waiting for an 800 to 1394b cable that I ordered on Amazon for my hub. We'll see if it works, otherwise I'm getting another interface that supports thunderbolt 3. Universal audio is the only one I know so far