2x CDJ 3000, latest firmware, both ethernet into a gigabit hub.
One laptop in the hub, Link 1 works fine.
Second laptop in the hub (to do changeover etc), little slow to recognise but comes up as link 2 so all good.
2nd laptop cannot load tracks. Just get loading message on CDJ. Waiting for several minutes. Both CDJs still play and laptop 1 can load tracks but with a huge lag. Entire system is completely unuseable.
Both laptops had Rekordbox libraries with over 10,000 tracks. I have no idea why this should make a difference but worth pointing out. Pro Link should be the simplest method, you connect, the link appears and nothing should happen until you drag a track to a CDJ in Rekordbox. Can you please try to PCs on ethernet with large libraries?