I am not sure why, but one of my boards works for 30m - 3H after a restart and then moves at 100 GH/s from 700 GH/s. Anyone facing the same issue?
I noticed my D9 slowed down to around 2.0Ths poolside about a week after the firmware update. A reboot seemed to fix the problem and it's back at 2.3Ths on Coinmine.
Did you notice if that board is heating up higher than the others?