Raid 1 not selectable during initializing AS3302T

[Broeckie]

I have a brand new AS3302T with 2x 6TB Seagate Iron Wolf HDD's and cannot initialize it as Raid 1. When choosing 1-click set up I have only the option "maximum capacity" resulting in a Raid single configuration. When choosing custom set up I can only choose the single option (JBOD, Raid 0 and Raid 1 are simply not selectable). Also, after set up as Raid single I cannot change it into Raid 1 via management option and storage management shows 1 volume of 6 TB so it is also not maximum capacity. Why is it impossible to set up my NAS as Raid 1? Are there any requirements related to the HDD's (formatting?), or to Windows 10 or BIOS?

[Nazar78]

There could be existing partitions on the other 6TB thus preventing it to be used as RAID array. Check that first, Google how to check for partitions.

[Broeckie]

There could be existing partitions on the other 6TB thus preventing it to be used as RAID array. Check that first, Google how to check for partitions.

Both 6 TB HDD's were brand new and installed immediately after unboxing so this cannot be the issue. Anyway thx for your suggestion.

[Nazar78]

You'll never know until you check it. It does happened.

[Broeckie]

Apparently the SATA connector was broken, so I had to return the NAS for a new one. Case closed.