The Synology DS1623xs+ uses DX1222 expansion units instead of the usual DX517

Six internal bays is standard for this class, but the DS1623xs+ takes a different expansion path than its siblings. Instead of the ubiquitous DX517, it pairs with DX1222 units — each adding 5 more bays for a total of 16. If you’re already in the Synology ecosystem, that’s a quirk worth noting before you buy expansion hardware.