WD PR4100: access for accounts from the AD domain does not work

[AllanStark]

There is a small AD domain company.local (DC: Windows 2012R2).
I have updated the device to the latest (5.10.122) firmware.

Joined the WD NAS device to the AD domain:
Workgroup: COMPANY
Local Master Browser: OFF
SMB Protocol: SMB2, SMB3
NT LAN Manager: NTLMv2 only
Active Directory Status: Connected to COMPANY.LOCAL

Time and TimeZone are correct and equal to the AD domain.

After connecting to the domain, it became possible to add domain accounts and groups to folder permissions.
I have added several accounts to one of the folders to check. However, these users cannot connect, they receive a message about the need to enter their login/password when trying to access the network folder.
The logs show messages like: “2021 Mar 08 08:11:45 SAMBA CIFS: Authentication for user [COMPANY\user] has FAILED.”

I have tried rebooting workstations from which users were trying to connect, but with the same result.
An attempt to enter correct AD logins and passwords in the window that appears does not give any result.
Trying to log into a folder under local device credentials (like NASNAME\admin) works fine.

[SBrown]

@AllanStark the following articles will help.

My Cloud Active Directory Prerequisites and Limitations

Answer ID 6122

Private Shares are Inaccessible (Access Denied) After Joining a My Cloud to an Active Directory Domain

Answer ID 11814

[AllanStark]

Many thanks! It helped.
My problem was that I didn’t add all AD groups, including nested ones.
I have to admit that this is very non-standard setting of permissions for accessing network folders…