I'm helping a client who was recently acquired by a larger firm. They still have their data servers on their original domain, Y, but the new firm is providing them with laptops connected to domain X. To access mapped network drives from domain Y, users have to enter credentials in Windows Credential Manager. However, they've been experiencing a significant delay of 20-30 seconds when trying to open Word or Excel files from these mapped drives. In contrast, computers still on domain Y open these files instantly. This issue occurs even when the laptops are on the same local network, so I suspect it's the domain difference causing the slowdown. Has anyone else faced a similar problem? For reference, the servers are on Windows Server 2022 and the clients are using Windows 11 24h2.
5 Answers
This is definitely a DNS issue. Windows first tries to connect to the servers using the FQDN of the new domain, which causes a delay of about 20-25 seconds before it times out and tries the old domain credentials. I recommend testing the mapping on a workstation using the IP address instead of the FQDN.
I encountered a similar issue before. It might be related to how the documents were created from templates that are no longer resolvable in DNS. Try to check if you can resolve the DNS name for any of the SMB servers on domain Y from the laptops on domain X. Sometimes, just pointing the DNS address to 127.0.0.1 can resolve the issue and speed up opening documents.
I'm dealing with a comparable issue right now involving devices that are hybrid joined versus those that are Entra joined. We're using hybrid identities with cloud Kerberos trust. The drives are mapped using FQDN, which might be affecting performance.
Have you checked if they're using trusted network locations? It could be that the new mappings need to be added.
I've experienced slow name resolution before when the old domain resources are not accessed using the fully qualified domain name (FQDN). Are there any DFS setups in use? Also, check whether the DNS configuration, like conditional forwarders, might be pointing to a slow DNS server in the old domain.
I think using tools like nmap could assist in diagnosing this kind of problem.