A computer that runs one of the versions of Windows that is listed at the beginning of this article, if you map a drive to a network share, the mapped drive may be disconnected after a regular interval of inactivity, and Windows Explorer may display a red "X" on the icon of the mapped drive. However, if you try to access or browse the mapped drive, it reconnects quickly.
This behavior occurs because Windows NT Server 4.0, Windows 2000 Server, and Windows Server 2003 can drop idle connections after a specified time-out period (by default, 15 minutes) to prevent wasting server resources on unused sessions. The connection can be re-established very quickly, if required.

Affected Windows Operating Systems

The above behavior occurs if the network share computer runs
  • Microsoft Windows NT 4.0
  • Windows 2000
  • Windows XP
  • Windows Server 2003.


To resolve this behavior, change the default time-out period on the shared network computer. To do this, use one of the following methods.
NOTE: You cannot change the default time-out period for Microsoft Windows 95-based computers and Microsoft Windows 98-based computers that have shared resources.

Registry Editor

You can use the Registry Editor to increase the default time-out period.
NOTE: You cannot use this method to turn off the autodisconnect feature of the Server service. You can only use this method to change the default time-out period for the autodisconnect feature.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
To do this, follow these steps, and then quit Registry Editor: 
  1. Click Start, click Run, type '''REGEDIT''' (Windows 2000, Windows XP or Windows Server 2003) or type '''REGEDT32''' (Windows NT 4.0), and then click OK.
    • REGEDIT (Windows 2000, Windows XP, Windows 2003)
    • REGEDT32 (Windows NT 4.0)
  2. Locate and then click the following key in the registry:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parametersValue: KeepConn Data type : REG_DWORD Range : 1 to 65535 (sec) Default value: 600 sec = 10 mins 

    NOTE: The client side session is automatically disconnected when the idling time lasts more than the duration that is set in KeepConn. For this reason, the session is disconnected according to the less set duration value between AutoDisConnect and KeepConn. To modify the timeout duration in the client side during a UNC connection, specify the arbitrary time in KeepConn from registry value.

  3. In the right pane, click the autodisconnect value, and then on the Edit menu, click Modify. If the autodisconnect value does not exist, follow these steps:
    1. On the Edit menu, point to New, and then click REG_DWORD.
    2. Type autodisconnect, and then press ENTER.
  4. On the Edit menu, click Modify.
  5. Click Hexadecimal.
  6. In the Value data box, type ffffffff, and then click OK.
NOTE: Since you cannot disable the connection timeout rate, setting the Value data box to ffffffff sets the timeout rate to its highest value of 4294967295 seconds.  This means that if don't reconnect to that connection within 136 years, it will probably disable itself.  (If this may be an issue to you, you may want to reference this article)

Command Line

NOTE: If you use this method, you may turn off the autotuning feature for the Server service. 
To change the default time-out period for the autodisconnect feature of the Server service, open a command prompt, type the following line, and then press ENTER 
net config server /autodisconnect: ######
NOTE: ###### is the number of minutes that you want the server to wait before it disconnects a mapped network drive. The maximum value for this command is 65535. 
NOTE: If you set the autodisconnect value to 0 (zero), the autodisconnect feature is not turned off, and the Server service disconnects mapped network drives after only a few seconds of idle time.
To turn off the autodisconnect feature, open a command prompt, type the following line, and then press ENTER: 
net config server /autodisconnect:-1

Additional Information

Additional Information on this issue can be found in the Microsoft Knowledge Base.
Most of the information from this article was obtained from the Mapped Drive Connection to Network Share May Be Lost article found in Microsoft's Knowledge Base.
Microsoft provides additional information in the following articles:

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Last Modified On: August 21, 2018