Hi there,
My suggestion would be to use the Storage Migration Service. Storage Migration Service makes it easier to migrate any storage to Windows Server or to Azure.
It provides a graphical tool that inventories data on Windows, Linux, and NetApp CIFS servers and then transfers the data to newer servers or to Azure virtual machines.
The below articles shreds insights about the process and for Synology you can get the same kind of articles from the Synology Knowledge Center.
Use Storage Migration Service to migrate a server https://learn.microsoft.com/en-us/windows-server/storage/storage-migration-service/migrate-data
Storage Migration Service overview https://learn.microsoft.com/en-us/windows-server/storage/storage-migration-service/overview
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