I have 2 EX4100 units and i use them sparingly. Last time i had them turned on was in October 2017. I turned them on last weekend and updated the firmware. I noticed that i could no longer access the drive by \ \sharename\Share, only by \ \IP Address\Share.
After that, i noticed i had to pull the power plug because the unit locked up and the power button would not repsond even after being held for a minute. That happened 1 or 2 times last weekend and then again this weekend when i had it powered on. I didn’t have both on, just 1 for now although i did update both firmwares.
My guess is whatever firmware updates have happened since October is the cause.
I have always had them hooked up to a UPS and use 1 power supply each.
I have all cloud and power saving features turned off. I was running about a 6tb backup from the EX4100 to a 8tb USB Drive and it even hung up during the copy at some point, so network activity is not enough to keep it from failing as i have seen some people suggest.
At this point, seeing no sign of it being resolved, I am going to just keep it turned off and maybe focus on getting another 8TB USB drive and then see if they ever fix it with a new firmware update.
I hope my post helps in diagnosing it, though.