Have you checked at what speed your computer’s WiFi is connecting at? What brand/model is the router?
As to copy speeds. There are a number of reasons why copy speed isn’t what people expect it to be. Namely one rarely if ever gets the advertised maximum speed of their network equipment. Then there is the network speed of the NIC ports on the computer/router, the hard drives (both on the PC and the My Cloud), network overhead, WiFi encryption, etc. that all contribute to slowing down the copying speed. Use Gigabit Ethernet from end to end if at all possible.
Start by reading the following thread:
Next, read the following two links that explain why one doesn’t normally see the speeds they expect.
http://www.tomshardware.com/reviews/gigabit-ethernet-bandwidth,2321-3.html
http://www.speedguide.net/faq/what-is-the-actual-real-life-speed-of-wireless-374
Further we have several threads that contain examples of copy speeds. Here are some of those threads.
https://community.wd.com/t/performance-benchmark-results/151741
