AD Domain Joining Error

Setup & Installation
1

I’m trying to join the DXP6800PRO to a Windows AD domain, but I’m having trouble because an error keeps popping up.

When I proceed via Control Panel → Domain/LDAP → Wizard, the error shown in screenshot1.png appears.

screenshot1
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I clicked “Details,” and I entered the “Domain account” and “Domain password” in the format shown in screenshot2.png. (The content is just a placeholder! I’m using the correct credentials.)

screenshot2
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I tried entering the “Domain account” in the format “hoga@domainname,” but that didn’t work either.

If anyone knows how to fix this, please help!

The System Version is 1.14.1.0.107.

2

Hi,
Did you get/find any solution for this?
I have the same issue. Tried all approaches, no breakthrough.

Thx,
BM

3

  • try these steps !!

    1. DNS Server Configuration (Most Common Cause)

Linux domain joins require resolving specific Active Directory SRV records (e.g., _ldap._tcp.dc._msdcs.yourdomain.com). If the NAS uses a router or public DNS (like 8.8.8.8 or 1.1.1.1), it will fail to discover the Domain Controller.

  • Fix: Go to Control Panel → Network → Network Interface.

  • Set the Primary DNS Server specifically to the IP address of your Active Directory Domain Controller.

  • Do not use external DNS servers as the primary DNS.

2. Time Synchronization (Kerberos Constraint)

Kerberos authentication strictly enforces time synchronization. If the clock difference between the UGOS Pro NAS and the AD Domain Controller exceeds 5 minutes, domain joining will fail silently or throw generic credential errors.

  • Fix: Go to Control Panel → General → Date & Time.

  • Enable NTP Synchronization and point it to your AD Domain Controller IP address, or ensure both the NAS and Domain Controller sync with the same time server (e.g., pool.ntp.org).

3. Domain & Credential Syntax

In the UGOS Pro Domain Join Wizard:

  • Domain Name / FQDN: Enter the Fully Qualified Domain Name (e.g., corp.example.com or ad.mydomain.local), not just the NetBIOS name (e.g., CORP).

  • Domain Account: Use an account with rights to join workstations to the domain (such as a Domain Admin or a delegated user).

  • Format:

    • Try pure username: Administrator

    • Try UPN format: Administrator@corp.example.com

    • Try Down-Level format: CORP\Administrator

4. Required Network Ports

Ensure no internal firewall or subnet routing blocks traffic between the NAS and the Domain Controller across these required ports:

Service Port Protocol
DNS 53 TCP/UDP
Kerberos 88 TCP/UDP
LDAP 389 / 636 TCP/UDP
SMB 445 TCP
NetBIOS / RPC 135, 137-139 TCP/UDP

5. CLI / SSH Advanced Diagnostic (If Wizard Still Fails)

If the GUI wizard continues to error out, SSH into the NAS to test resolution and run a manual test:

  1. Verify DNS Resolution:

    Bash

    nslookup yourdomain.com
nslookup _ldap._tcp.dc._msdcs.yourdomain.com

  2. Check Domain Reachability via Samba:

    Bash

    net ads lookup -S <DomainController_IP>

  3. Attempt CLI Join to View Detailed Errors:

    Bash

    net ads join -U "Administrator"
4

Thank you!
I tried all the approaches and found out the killer was the DFL and the FFL. both are 2025.
After extensive testing, I found that my UGREEN NAS joins and fully integrates with fresh Active Directory forests running Windows2016Domain/Windows2016Forest functional levels (Server 2019 and 2022), but consistently fails at the final “domain server” validation step against forests running Windows2025Domain/Windows2025Forest, despite DNS, LDAP, and Kerberos all working correctly.
So, for now I will stay with 2022DCs and DFL&FFL at 2016.
Al-the-Best!
BM