To get my MyCloud to work reliably, I set my DHCP lease time to 365 days after setting my MyCloud to static. It seems to have “fixed” or delayed the problem. It seems to me that the MyCloud still requests an IP address and gets mixed up even if you set a static IP address.
ReplayTV’s had a similar bug that could be overcome by assigning fixed IP addresses to a MAC address, but I don’t think that works here. Regardless, this history is why I tried it.