4 TB only shows up as 1.67 TB

Hello, I’ve recovered 2x 4 TB HDD’s from a QNap (used in a Raid5). I want to use them as spare drive in a desktop. Only, when I format them, they show up with a capacity of 1.67 TB. My operating system is Win10.

Repartition them, then format them. Maybe use Windows Disk Manager to do that or Mini Tools Free Partition Wizard.