Strange playback issues with the CDJ-3000 encountered on stage

I use 4 CDJ-3000s and 1 DJM-A9 on stage, all linked to the same 8-port switch (Netgear GS308v3, without routing function). The signal between the CDJs and DJM is digital. The switch has two Ethernet cables going to the FOH for ShowKontrol.
During my DJ set, CDJ #1 was in pause mode, but when I pressed play on CDJ #2, CDJ #1 started playing as well. This issue has occurred three times so far. Although it's rare, it has happened during large events like EDC. I'm not sure if anyone was encountered a similar situation or know what might be causing this.