first off firmware upgrades should never be done without consulting people for other solutions.
Since you did new firmware I am not sure it is the same problem.
But let us pretend the firmware upgrades did nothing good or bad.
It looks like the psu has enough balls and is not the problem
So I ask how are you internet connected?
wifi?
a cat 5 cable over 15 feet?
If you are wifi do a eth cable
If you are eth cable do a better quality
here is a good one.
https://www.amazon.com/dp/B01ELMYKQW?m=A1R6CPF0VN02MD&ref_=v_sp_widget_detail_page&th=1he has many lengths.
you could also use 2 of the 3 boards and do not connect power cables to the third one.
if 2 boards work you may have a weak psu.
bad eth cables ---- switch eth cable
weak psu's _------ try my idea
bad controller ---------- buy a new part
bad hash boards ------- buy a new part