I too, have been having issues with an external drive “disappearing” from the network, as well as it screwing up the MYCLOUD device itself.
Yesterday, while talking with a WD Tech, we decided to try something. SO far, about 36 hours later, things are still running fine, so maybe this “solution” could help some of you, although I don’t particularly like it.
Go into the MYCLOUD Dashboard, select Settings and come down to “Energy Saver.” The default is “ON”. Change it to “OFF”. Now, install your USB drive. Like I said, this may be premature, but it has been about 36 hours now, and all is well.
My External is a Hitachi XL-2000 2TB. ABout 3 years old. Hitachi says there si no way to keep the drive from sleeping. I am not sure if changing the MYCLOUD setting to off forces the unit to send a wak-up signal at regular intervals, but I just finished a 19+ hour backup to the external drive, and all worked well!
Here is hoping it continues to work, and that this helps someone else out there!