I have two identical 3TB MyClouds and have had them for 9 months.
While some of the early glitches have disappeared and are not occuring any more (like the drive disconnecting from a local network), they both frequently become inaccessible through Android / iOS apps, with error (0) on Android and with the following error on iOS.
Sometimes they stay online for a couple of weeks, at other times they are gone from the cloud in a matter of hours. All the time they are accessible on the local network. Ports on the router are opened, etc., and everything is configured properly.
Generally speaking the drive on which the media server / DLNA is turned OFF usually manages to stay accessible for a longer time, while the other usually fails and goes offline as far as cloud is concerned within a day.
Both are still on v3 of software.
After 9 months of delayed firmware updates, communicating with the support, installing special scripts which have enabled logging (provided by WD support), I am now just tired of trying to make this work. I will probably be buying one of Synology units and disassembling these two MyClouds and just using their drives.