Troubleshooting Lost Network Connections

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This article provides troubleshooting steps and suggestions that may assist you in solving network connectivity problems. Microsoft cannot guarantee the success of any specific steps provided in this article.


Windows for Workgroups may sometimes lose (drop) network connections. This problem is most likely to occur if one of the following conditions exists:

  • You are running a network installation (SETUP /N) of Windows for Workgroups.

    NOTE: Microsoft does not recommend running Windows for Workgroups from a network installation (SETUP /N) because doing so is a common stress condition that can cause a loss of network connections. If your system is run this way, store data and applications on a client or server that does NOT contain the shared Windows directory (created with SETUP /A); this appears to reduce the frequency of the problem.
  • Several people in a workgroup are running the same application from a server.

    NOTE: Network connections also can be lost when many users run the same application from a server (for example, 10 clients use the same installation of Microsoft FoxPro for MS-DOS). MS-DOS-based applications seem most susceptible to this problem, but Windows-based applications can be affected as well. Windows-based applications generally report segment load failures when the network connection is lost. MS-DOS-based applications that leave a lot of files open, such as database programs, are more susceptible to this problem.
If network connections are lost or dropped, the system or application may stop responding(hang), the network installation of Windows for Workgroups may become corrupted, and MS-DOS-based applications may produce unexpected results.

WARNING: If you lose your Windows for Workgroups connections, immediately save all open data files to backup files on your local drive or a remote drive where you still have a valid connection.

More Information

Loss of network connections can occur when you use any version of the redirector, but the basic redirector, invoked by using the "NET START BASIC" command, is most likely to have this problem. The problem seems to be caused by a timing issue in the NetBEUI protocol. It may also be related to the network buffer size because it occurs when data is being sent over the wire. In testing, this problem didn't occur unless the system was running under the conditions listed above; however, the problem may occur when a system is not under any stress, but this is very rare.

Other factors that can cause connection problems include the following:

  • Network cards: Some network cards are more prone to these problems than others.
  • Machine speed: The slower the machine, the more likely that its network connections may be lost.
This problem usually originates with the server but affects clients only.

Attempting to Recover

To determine if you have lost network connections, go to the server and use Net Watcher to see if the machine that is not responding still has a valid session open. This method does not always work because some applications can reopen the network connections. Some applications may not be affected by a lost network connection if they are not dependent on file pointers being maintained on the server.

Sometimes you can issue the NET USE command at the command prompt to determine whether or not a session has been disconnected. This technique works best when the machine is not using a network installation (SETUP /N) of Windows. Issuing the DIR command may restore the network connection and allow the application to continue or at least exit without causing the system to stop responding (hang).

You can also try to close all open files and attempt to quit Windows. If the problem results from a network installation of Windows having lost its network connections, you will get a message telling you that you do not have enough memory to complete the operation.

Avoiding the Problem

The following steps may help prevent this problem:

  • Increase FILES= to 128 or higher in the CONFIG.SYS file.
  • Increase FCBS= to 25 or higher in the CONFIG.SYS file.
  • Increase Sessions= to 20 or higher in the PROTOCOL.INI file.
  • Set NCBS= to 40 in the PROTOCOL.INI file.
  • Set NetHeapSize= to 52 in the [386Enh] section of the SYSTEM.INI file.
  • Set TimerCriticalSection= to 5000 or higher in the [386Enh] section of the SYSTEM.INI file.
  • If you are using a network installation of Windows (Setup /N) set maintainserverlist= to NO in the [network] section of the SYSTEM.INI file.

문서 ID: 90226 - 마지막 검토: 1999. 9. 17. - 수정: 1