panic/kernel reboots on Mac

I have a 5D with 5x4TB disks. 2 Volumes (one main and the other time machine).
I was running out of space and replaced one by one 3 disks with 6TB ones.
During and after replacing the 2nd one I notices spontaneous panic reboots on my Mac.
Drobo was running OK but the Mac acted like never before.

I disconnected the Drobo (and am now reverting to all 4TB disks) and the Mac was stable again.

Supposedly it should work with 6TB disks. This must be a Drobo software/driver issue.

Really unhappy.

6 TB drives should work.

Unless the drive(s) is/are problematic…

They should but in my case didn’t! They work now perfectly on a Synology.
After reverting to 4TB and reformatting the Drobo (loosing all my backups) kernel panics are gone.