Have you got Western Digital MyCloud ?
With the My Cloud personal storage device, you’re able to have reliable storage in one place for your photos, videos, important files – anything you save – and share it anywhere you have an internet connection. With the automatic backup and synchronization software, your content is up to date and accessible from all your devices.
However, most user complain about MyCloud keep disappearing off network. It on and off, sometimes we can find on network, most time it doesn’t.
Related to this topic, I’m using my WD MyCloud 4TB device as example. I guess it should be the same which model you are using, because it is using the same system.