Need help for shared permission and dual redundancy

Hi all, I have been using my ReadyNAS Pro (6 bays) for many years and upgrade (CPU, Memory, and OS) Now using OS 6.xx

Recently I lost all my volume (all red) probably a corrupt system files or Netdata screw something because after a reboot this happen.

I have all my files backup to an external USB drive connect to the NAS. So I factory reset and start from scratch. At the moment I use 3 x 3TB drives (X-Raid 5 mode) and I have 2 spares drives. I wanted to use dual redundancy with 4 drives but I never got the option

when I factory default. Can I change to dual redundancy from a X-RAID 5 mode without restart everything ?

Another issue with Shared folder permission. I have 1 PC which I use as Admin rights and have a NUC, media player, Roon to access music on the NAS. For many years I use Genie Timeline Pro to backup my files and documents. The backup times are slow and I found the restore not reliable and I lost some files because the software couldn't restore it. So I look for a backup software alternative and I end up with AOMEI Backupper Pro on sale.

When I create my shared folder on the NAS I select SMB (not legacy mode or SMB 1.0) and all users for permission but by default (anonymous to access shared folder) is enable. So I deactivate (anonymous access). For a reason AOMEI Backupper cannot write to my Shared folder "Backup" but what is strange I can access and write to the shared folder "backup" with the PC.

The only way I can make backup with AOMEI Backupper is if I set the permission to "anonymous can access shared folder"

All Users as permission don't work. If I remember I didn't have this issue with Genie Timeline Pro.

What could cause the backup software to not have access and write on my shared folder if the anonymous access is not enable ?

Is there a security issue by using the anonymous user to access my shared folders ?

Thank you