Many issues can affect client network connections, and identifying specific problems can often be difficult. What do you do when a Windows 2000 client machine randomly logs itself off of the network and will not maintain its connection?

That’s just the problem that computer systems engineer Maxwell Edison recently posted in our Technical Q&A forum. Edison said that his network servers run WinNT 4.0, and all of the clients but one run Win9x. The one exception among the clients is a laptop running Win2K Pro. Edison reported that this laptop randomly logs itself off of the WinNT domain and wanted to know what he could do to fix it.

TechRepublic members weighed in with a number of suggestions that helped Edison troubleshoot the problem and that can be used to resolve connectivity issues in general.

What to look for
If you have a client that persistently logs itself off the network like this, then use the following tips from TechRepublic members to diagnose and resolve the issue.

Suggestion #1
Application trainer and consultant Doug Klippert suggested that the problem might be related to master browser election and said Edison should try turning off the browser service on the Win2K client machine. Klippert pointed to Microsoft Knowledge Base Article Q188001 for information about the browser service and suggested that Edison consult Article Q188305 for troubleshooting tips, including the use of the “browstat” tool from the Windows Resource Kit.

In addition to these articles, Klippert pointed to Article Q191611, which contains information about issues caused by multihomed systems, which the article says can create “unexpected and undesirable effects with the browser service.”

Klippert added that one step in troubleshooting this issue is to check the registry settings for the browser service, located in this key:
\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Browse r\Parameters\MaintainServerList

Values for the service are:

  • No—The service never acts as a browser.
  • Yes—This forces election if no MasterBrowser is found; otherwise it becomes a backup browser.
  • Auto—The service is a potential browser. The MasterBrowser will tell it to either become a browser or not. This is the default for NT Workstation and Server.

Suggestion #2
Tim Walsh of Sparta Inc. said that Edison should check the security settings on the client:

  1. Click Start | Settings | Control Panel.
  2. Double-click Administrative Tools.
  3. Double-click Local Security Policy.
  4. Expand the Local Policies folder and select Security Options.

Walsh said that the Amount Of Idle Time Required Before Disconnecting Session setting might be the culprit, since it could cause persistent logoffs if it’s set too low.

Walsh also suggested looking at event logs of the Win2K machine and the primary and backup domain controllers. He said that Edison should use the event logs to verify whether the client is logging off of the network or rebooting altogether, which might indicate a problem other than connectivity.

In addition, power management settings for the NIC can cause disconnects if the NIC is being turned off to save power, Walsh noted. The NIC itself could also be a problem, so he suggested replacing it with a spare to eliminate the possibility that a faulty NIC is causing the disconnections.

Suggestion #3
Member Ninet4 offered some other suggestions for troubleshooting the problem. Ninet4 said that if DHCP is being used and the DHCP service is shut down for any reason, IP connectivity is lost. Ninet4 suggested that Edison check to see whether the DHCP service is running the next time the Win2K Pro system logs off of the network. If it’s not running, Ninet4 said, start it and renew the adapter.

Network engineer Joseph Moore agreed with Ninet4’s assessment and added that Edison should check to see whether certain drivers are running when the system loses the connection. If the drivers NDIS.SYS, NDISWAN.SYS or ADF.SYS fail, it could be the cause of the disconnection. Moore said that it’s possible that the drivers might fail as a result of the problem but that their failure might very well be the cause of the problem as well.

Problem solved
Edison reported that following these suggestions helped him resolve the issue. He said that he worked through these troubleshooting tips, and the Win2K Pro system no longer randomly logs itself off the network. He’s not sure if one particular suggestion provided the fix or if it was a combination that did the trick, but the end result was a positive one: no disconnections.

If you experience a connectivity problem with a Windows client machine in an NT domain, here are some factors you can look at to determine the cause and repair the connection:

  • Browser election service
  • Idle time disconnect security setting
  • NIC power management settings
  • NIC drivers
  • DHCP service issues

Working through the fixes these TechRepublic members provided should help you find the culprit so you can repair the problem.