Permissions bypassed for new Domain User

We have several DL4100 and all suffer the same issue.
We add a new user to our Windows Domain Controller and this shows on the NAS with the expected Deny permissions on all the shared folders. We then give the new User permission to access the folders they need. However, when we check for access over the network to the Deny folders the new User can still access the Deny folders too??
If we reboot the NAS the folder permissions are populated correctly.
If I access the User profile on the NAS and specifically re-click the Deny on the folders they should not access then the folder become inaccessible.
This means i have to click the Deny on each folder (even though they are already showing Deny) as well as the Allow, otherwise the User can access the files they do not have permission to. This is a serious flaw and causing security concerns on our organisation.

As you have discovered the DL’s are only good for public shares. If you want to control user permissions you need a Windows Server. You can also schedule daily backups with a calendar to restore from to an external USB drive with Windows Server