Did you set the static IP address within the My Cloud Dashboard interface? Or did you reserve an IP address for the My Cloud within the router’s administration page?
If you set a static IP address for the My Cloud through the My Cloud Dashboard. Then, as a troubleshooting step, try performing a 4 second reset. This will reset the DHCP setting on the My Cloud back to default where it will attempt to obtain an IP address from the router.
How to Reset a My Cloud (single bay) Device