Rekordbox Link

you do not connect them via usb to use the LINK function, You use the ethernet cables. 

If you want to share a usb drive between 900's you can simply plug 1 ethernet cable into the 900's and link them together. To add the laptop into the mix, you would need a network switch link a Netgear, Linksys, etc.... plug the laptop and 2 900 ethernet ports into the switch, a link button will appear after 10 or so seconds on the bottom left of RB, click on it and you are linked to play tracks

Still not working. really getting frustrated with this set up.

connected both CDJ's to D Link switch, they link up and establish fine player 1 and 2. get no response from rekordbox, no link button appears at all.

whats the story here? ive got all recent firmware and latest rekordbox but still cant link.

any help MUCH appreciated

what kind of laptop and OS you have?

First thing, disable wireless on your laptop.  You CANNOT link non-Nexus equipment if there is a wireless connection connected or even enabled on your laptop - even if you have a network cable connected.  Disabling the wireless on the laptop will - should - make the Link icon appear in RekordBox.