The problem is likely your controller.
To get your 6 boards to work on one controller, copy the 18 pin data cable connection layout from the forum link posted before.
If you plug them into the wrong plug the controller won't recognise the hashing board.
I have the same problem with one of my controllers.
One of my boards in one miner won't show up unless I don't power on my controller board for about 10 minutes after the hashing boards. But they still drop out eventually. Sometimes 2 days, but other times, like right now, within minutes of running.
Actually the problem is in hashing board, I have tested few working controllers with machines, while it's controller is all fine, it's even shows the ASIC chips, temperature and fan rpm but it doesn't hash even after few minutes the controller got unaccessable while machin keep turn on the red light.