DJM-2000 Nexus + 3x CDJ3000 - DJ Link not working after firmware update.

 I bought a new setup - 3x CDJ3000, DJS1000 and RMX1000. Since I am extremely satisfied with my current DJM2000nexus mixer, I refused to upgrade to V10. It seems unnecessary to me. However, after connecting the DJLink with a network cable and after updating the CDJ firmware from the original version to 3.12 and higher, it gives me the same problem. Shared USB Flash media are constantly connecting and disconnecting. The same can be seen on the DJM mixer after switching the display to show which device is the Master and which is the Slave - the individual players are constantly connecting and disconnecting on the display. It cannot work with this upgrade. Unfortunately, I played the original version 3.11 and I can no longer find it anywhere. Now I only work on the old vekajen etírzi 2.20. With this everything works, but I can't update the CDJ. The mixer has the latest firmware, there is no newer one. Does anyone have any advice? Thank you, Petr B.