Many of getting this problems, May be L3+ have weak hardware, There are many complaints about L3+ miner on the forums and websites. I also got problem in 3 week. And aslo difficulty increased soo much. We dont get earn more but, Bitmain company Earning Super. We are the fools, buying the miner.
I've found complaints on forums to be a bad indicator as to how reliable a product is. The vast majority of people without problems don't post. To date, we've received 110 AntMiner L3+ units straight from Bitmain. Thus far, we've only identified 1 bad hashing board. It's obviously still a young product, but we're finding them to be much more reliable than the S9 series.
Dude, may I know what is the chip temperature of your L3+ when running and what is the environment (air-con server room or just air-flow cooling) it is running in? I also had 75 L3+, which means 300 hash boards, the total dead hash board after 3 weeks are 20, which is around 6.5%. The chip temperature is around 63-65c, sometime goes to 69-70 but never higher and I use air-flow cooling only, all run at 384 freq. Not sure what I did wrong, but in my coin mining group, many members have the same situation. I really appreciate if you can share your experience regarding this machine.