CDJ 3000 and MDJ 900 Nexus 2 does not work touch preview

I have 2 cdj 3000 and 1 mdj 900 nexus 2 connected by ethernet through an ethernet hub and I can't get the touch preview option to work. I activate the CUE link button in the mdj and when I press on any song in the preview nothing sounds. I've already tried changing the ethernet cables and hub and it still doesn't work. Can you help me?