Hello everyone… 
I am currently in the process of setting up a Univention Corporate Server (UCS) environment to manage a small network with around 20 users. My UCS instance is running as a domain controller, and most features seem to be functioning well so far. However, I’ve hit a snag when trying to join Windows 10 clients to the UCS domain.
Here’s the issue:
- On the Windows client, I go to “System Properties” > “Change Settings” > “Domain” and enter the domain name configured in UCS.
- I am prompted for the administrator credentials, which I provide (these credentials work on the UCS server).
- After a brief loading screen, I receive the error message: “The specified domain either does not exist or could not be contacted.”
What I’ve done so far:
- Confirmed that the Windows machine can ping the UCS server by hostname and IP address.
- Verified that DNS is configured correctly on the Windows client to point to the UCS server.
- Checked that the UCS server firewall is allowing relevant ports for domain communication (e.g., 53, 88, 389).
Despite this, I still can’t join the domain.
I check this: https://help.univention.com/t/windows-clients-can-not-join-to-the-ucs-domainaws-training But I have not found any solution. Could anyone guide me about this? Has anyone encountered a similar issue or have suggestions on what to check next? I’d appreciate any advice or steps to troubleshoot further.
Thank you for your help!
