Official comment
Hey PS,
Let's go over the different use-cases and from that you determine the cabling:
First, stand-alone. This is using the products without a computer. You need to run an ethernet cable and analog audio (RCA) cables from the XDJ-XZ to the XDJ-1000.
Second, rekordbox export mode. With this mode you would run the ethernet cable between the XZ and 1000, and either an ethernet or USB cable from the XZ to the computer, as well as the analog audio (RCA) cables.
Third, rekordbox performance mode. Connect USB cables from each product to the computer. No need to run audio cabling as the XZ is configured as the audio output for all 4 channels of audio from rekordbox.
Fourth, Serato. Same as #3; just USB cables.
There is no router required as the XZ has 3 ports.