3.12.0
As I feared. Your S4's are working fine - it's just that someone is stealing your hash.......
Bitmain fail.
Can this be prevented in any way in the mean time? Use of a proxy, or something? Why doesn't this happen with all pools?
Not that I'm aware of & it can.
I doubt that this is the problem, even though it is a very big one. The problem here is that Bitmain have shipped out units before fully testing the firmware, as they themselves stated. That's just wrong.