New My Cloud Duo replacing My Cloud. Cannot get discovery to recognize both drives

I just purchased a My Duo. I currently have a My Cloud device that will no longer be supported. I want to migrate all the data from the old device to the new device, but I cannot get WD Discovery to see both units. It recognizes the new one but not the old. What am I doing wrong?

Hi @TomRIggs,

Please be informed that we request to take a backup from NAS to USB, then you can back from USB to new NAS.

Please refer following articles:

https://support-en.wd.com/app/answers/detail/a_id/20227

https://support-en.wd.com/app/answers/detail/a_id/1946