E-8309: link acces error

Hi,

I've got multiple ' E-8309: link acces error'  and searched the forum and internet to no avail;

I have 2 XDJ's 1000 (ver. 1.0.5) lan connected to Rekordbox 4.1.0 (OS X 10.9.5), connected via a König 5-Port Ethernet Switch 100/1000 Mb/ps and Cat5e cable.

I've tried all this;

- Configured firewall and Little Snitch according to Pulse Youtube tutorial;

  https://forums.pioneerdj.com/hc/en-us/articles/205021519

- I've turned file sharing off, wifi off, firewall and little Snitch off.

I've checked this page, also to no avail: https://forums.pioneerdj.com/hc/en-us/articles/205021519

Any tips & tricks left ?

Kind regards, 

Michiel

p.s.:

THE SOLUTIONS THERE before posting:  Yes, I swear it!
1) Operating System: OS X 10.9.5 
3) rekordbox version: 4.1.0
4) Using LINK: Yes
4b) LINK Connection method: König 5-Port Ethernet Switch 100/1000 Mb/ps and Cat5e cable.
4c) UXDJ's 1000 (ver. 1.0.5)
5) Source: Hard drive 
5b) Connection type: network
5c) Does the device have multiple partitions: No
5e) With what utility did you format the device: OS X

7) Have you scanned your files for errors: Yes

7b) Have you scanned your drive for errors: Yes
8) Is rekordbox crashing at all: No 

9) Are you able to repeat / reproduce the problem: No 
9a) If yes, can you do it consistently: No 
10) Does the problem occur with one specific song: No