Do you have the players set to a manual player number or are they automatically identifying themselves?
cdj 3000 issues with link
i have recently encountered link issues where the 2 cdj3000 players don't share info at all and not recognised. you can't access the usb from one to the other. i tried a new usb and disconnected from my tp switch box and plugged players directly via ethernet cable which i also tried a new lead. i had to disconnect everything and power down units to get to recognise. this has happened several times now.