I read  some solutions. First try a good quality network cable. The next one is remove all cables of one hashboard and install one of the firmware updates from bitmain. In another thread somebody tried  the 550m Version but i wouldn't do that. Take the auto frequency first. Another guy wrotes  he insert all 3 pool adresses from  antpool an it works but he said nothing about bis Firmware. And one guy had issues with one fan so the miner reboot every  3 minutes  and doesn't load bmminer Version.

I have no time Next days to try out, maybe you. Pls tell me all