Hi, as you mentioned the drive does have a gigabit NIC, however is your complete network setup gigabit? Is you are accessing the drive over wifi, do you have a AC Router and you computer is capable of AC connectivity?
In regards of the drive heating up, what temperature does your drives reach? According to this post by a WD Staff member his drives had to reach 57 degrees celsius before having the fan turned up, although this was I believe in an older version of the firmware.
In regards of the drive not going into sleep mode, you may shutdown all the services that you may not use, like remote access.
