Ok i Think the FW has nothing to do with the drops i have tried Following FW:
Jan from Bitmain.
April from Bitmain
Graphs Nicehash
Smiths FW
July from Bitmain
I have tried them for periods of two weeks and still happens.. Im really getting frustated of not founding the problem.
The problem could be a firmware issue that has never been fixed from the first firmware iteration. Otherwise it would be a serial controller defect which i kind of doubt. It could be easily tested if someone had a unit that does this often and switch boards, see if its the same board or the other board that now has the problem.
