Have you configured the firewall per that guide and disabled any file sharing or other server software?

You mean this this guide ? http://forums.pioneerdj.com/entries/20118251-read-this-thread-before-posting-for-help-with-rekordbox

Me and my computer "Jack of all trades" friend will look my machine.

Yes; the guide from which you copied that list of questions / answers... there are helpful tidbits in there regarding your firewall (which is where I feel the problem lies without diving further). If you could please verify those are completely disabled and you have things like file sharing turned off. If you're wired, also disable your wireless.

Ok, we have now tried those things too (no file sharing and no wired) and we checked firewall but still problem occurs.

I just want to confirm -- the link DOES establish at some point, but then during use, it stops and loses the link?

Yes. First all goes normally and fine: link connection works but suddenly during use it stops.

We might have found the reason. Router thinks that link is Public (network) and we changed that to Private / Home. Last night it was working fine (i played about 3 hours with Pioneer 2000 CDJs old model) and now im going to test how 2000 nexus CDJs are working.
I will info if we founded solution.

Ok, seems like Pioneer 2000 (old model) works and stays Private / home but nexus model makes router link to Public. I think this is problem, not sure.

@Meke > So it sounds like the problems is isolated to your network settings and not rekordbox or the players. One of the instructions in that readme was a link to ensure your network-type was private and not public:

http://tipsandtricksforum.com/thread-252.html

You need to check this if you change your configuration.

Yep, i need to change my router to private / home from public and then link works.

I also have the same issue. Running Windows 7, On a Sony I7 with 16gb ram using the pro-link and 2 CDJ900's. I have no firewall activated on on my Ethernet nework. I have quality Ethernet cables the shortest possible. I could find to purchase. I have all unnecessary software disabled including my Anti-virus and Wi-fi. I usually only experience this issue after around 2 plus hours or more of playing. The interesting thing is usually it's only one player or the other that will drop the link. I don't have to restart Rekordbox. I usually just have to un-plug the Eternet cable of wich ever player dropped and then wait for Rekordbox to re-initialize or recognize which ever player dropped the link sometimes. I have to wait 1-2 minutes or more for this to happen, however. I never have to restart Rekordbox itself.

Have you scanned your computer for malware and viruses?

Yes, I've scanned for Viruses and Malware. I also just did a fresh Windows 7 install about 2 months ago. I use this laptop specifically for Djaying and Music production. I rarely if at all use this laptop to surf on-line, prior to using the pro-link. I even had all network adapters disabled. I feel pretty confident in this systems network security...lol

Yes, I've scanned for Viruses and Malware. I also just did a fresh Windows 7 install about 2 months ago. I use this laptop specifically for Djaying and Music production. I rarely if at all use this laptop to surf on-line, prior to using the pro-link. I even had all network adapters disabled.

@Grant > Have you tried connecting only one player directly to the ethernet of your computer?

I'm not sure i understand what you mean? I haven't experienced the issue since the most recent update.