The QB-35US3-6G has 2 connections for data transfer: USB3 and eSATA. The DS720+ has the same connections. I do not own a Synology DS but a similar model from QNAP. In my case, it is connected via eSATA and the 4x10TB discs installed in the device work without any problems. You can share them as a share I would now expect this to work the same way with the DS720+.