There are a variety of issues that can affect transfer speed including the OS, the network card being used and its settings. Just as an FYI there are several prior threads discussing speed issues, charting those speeds, and some potential causes of slow speeds. Note it is well known the transfer speed from PC through the WD My Cloud to an attached USB drive on the My Cloud is abysmal.
Here are some of those threads if one hasn’t seen them.
before you pack up your WD and return it, let’s talk about Copying Speeds!
WDMyCloud (2TB) slow under Windows 10 & some programs can’t access files
*FIXED* Time Machine speeds - Want to ensure I’m maximizing
