My Cloud OS 5 is available for My Cloud PR2100 and PR4100.
Please refer to this post to learn how to update your device to My Cloud OS 5:
My Cloud OS 5: Firmware Availability and Supported Devices
My Cloud OS 5 How to Update From My Cloud OS 3
My Cloud OS 5 is available for My Cloud PR2100 and PR4100.
Please refer to this post to learn how to update your device to My Cloud OS 5:
My Cloud OS 5: Firmware Availability and Supported Devices
My Cloud OS 5 How to Update From My Cloud OS 3