My guess is the unstable voltage you feeding the miner with, when the voltage drops the miner lower the frequency and voltage in order to draw less amps (or whatever the proper term might be) and as a result the hashrate will drop too, once your voltage goes above 220v again it goes back to mining full-blast, once the voltage falls below the threshold the miner reboots/stop mining.
if you confirmed that above is not the issue, then your internet connection/network is , if non of the previous issues exist , then it's a temperature related issue, the miner could be going through the same process as the voltage drop when it get's hot, thus the hashrate fluctuate.
It's highly unlikely that a faulty miner will mine perfectly for sometime , mines at lower hashrate then reboot, and then out of the blue starts mining perfectly, that does not sound like a faulty miner to me, a faulty miner acts bad nearly 100% of the time.
Topic: WhatsMiner M20S fluctuating hashrate (Read 108 times)
Hi guys.. I have a problem here and I hope you guys can give some advice. I just installed my M20s 4 days ago... it was running fine at first but after around 14 hours to 16 hours... it fluctuates and the hashrate keeps dropping and on and off by itself a few hours and then it runs again... it has been like this for these few days already. Sometimes it shut down and I reboot it to start again. Anyone facing this problem before? Or am I unlucky to get a faulty miner 
hard to say.
do you check fan speeds and temps?
if fans are doing over 6000 rpm and the gear is over 75c the room could be too warm.
these are power hungry units.
do you use proper cables?
is your power 210 volts or 220 volts or 230 volts or 240 volts. or worse yet do you sag to 195-200 volts?
Hi guys.. I have a problem here and I hope you guys can give some advice. I just installed my M20s 4 days ago... it was running fine at first but after around 14 hours to 16 hours... it fluctuates and the hashrate keeps dropping and on and off by itself a few hours and then it runs again... it has been like this for these few days already. Sometimes it shut down and I reboot it to start again. Anyone facing this problem before? Or am I unlucky to get a faulty miner
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