Did you see Bitmain has new firmware for it from 2019...

https://service.bitmain.com/support/download?product=AntMiner%20L3%2B

There are also alternative optimzations from Hive Os and others for this miner.  I am looking to see if Bitmain locks your SSH ability with that firmware.  So read up before doing it...but may be as simple as old firmware.