It usually works fine within my wifi network. Outside the wifi network it works on and off.
Which generation of My Cloud do you own 1st or 2nd? If using a browser outside of your network, which one? What device or devices are you using when trying to get cloud access outside of your network?
So far I haven’t had any problems outside of my network. I mainly use my Samsung Galaxy S7 phone and I use both wi-fi and LTE to connect. I use the mobile app and if needed Microsoft Edge.