Nas and/or DAS thunderbolt

[ed]

If you can not return them and get USB3.1 gen2 (10Gbit) version, you may consider getting 10gbit USB docking station which you could slide those drives into. Or empty enclosure such as icy dock or Terramaster. Just make sure your Qnap has 10gbit port or PCIe upgrade slot.

I hope this helps.