External HDD on NUC running ROCK

I have a 2TB internal drive on my NUC which is now full . I was planning to move to a 4TB HDD but the drive is not being recognised . 2TB and 500GB drives are both recognised
I then vaguely reading ages ago that there was a 2TB limit on HDD’s on ROCK , is that the case ?

To clarify all drives I refer to are external

I don’t think so. Have you already read ROCK: Storage Basics? Are you using a compatible drive format on the non-recognized drive?

I have two HDDs attached to Rock - 5TB and 8TB.

This was because of physical size constraints of HDDs fitted internally in a NUC - drives can’t be more than 9mm thick. It is still the case, I believe.

Looks like it was NTFS format it didnt like . still have work to do to clear space on an EX-Fat drive , will let you know how i get on . Thanks