The issue with my MyCloud EX4100 is about Internet. My device is connected to the PC with ethernet cable + connected to Internet with another ethernet cable directly to the router.
I can access to the Dashboard but if I go on this section - Settings - Network: No Internet access
My Operating system is Windows 7 Ultimate 64 bit, MyCloud firmware 2.30.165.
Try connecting it only to the router, and connect your PC to the router. That’s what the router is for; to route data between the different devices on your network.
I assume you have enabled Cloud Access on the MyCloud?
You may want to see the dedicated EX Series subforum to see if there are similar issues to those you are experiencing. This subforum (My Cloud) is generally for a different device, the single bay/single hard drive My Cloud model(s).