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The network connection is lost on a Hyper-V virtual machine

This article (KB2223005) provides a fix for a network connection problem in which the connection drops on Windows Server 2003-based or Windows XP-based virtual machines (VMs). This problem occurs when the VM is running under a heavy load. For detailed information, see the “Symptoms,” “Cause,” and “Resolution” sections of this article.

To download the fix for this issue, click the View and request hotfix downloads link that is located on the upper-left of the screen.
Consider the following scenario:
  • You install the Hyper-V role on a computer that is running Windows Server 2008 R2.
  • The computer hosts a VM that is running Windows Server 2003 or Windows XP.
  • The VM is running under a heavy load.
In this scenario, the network connection for the virtual machine is lost. Additionally, you must repair the network adapter or reset the VM to recover from this issue.
This issue occurs because the NDIS 5.0 miniport driver does not handle network packets correctly when the allocated memory for a buffer is almost exhausted.
This hotfix is also available at Microsoft Update Catalog.

After you install this hotfix on the Hyper-V server, you must update the integration components in the VM that is running Windows Server 2003. To do this, follow these steps:
  1. Use Hyper-V Manager to connect to the VM.
  2. The Virtual Machine Connection tool starts.
  3. On the Action menu, click Insert Integration Services Setup Disk.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this hotfix, you must be running Windows Server 2008 R2. Additionally, you must have the Hyper-V role installed.

Restart requirement

You must restart the VM after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows 7 and Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional file information

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
981836Network connectivity for a Windows Server 2003-based Hyper-V virtual machine is lost temporarily in Windows Server 2008 R2

Additional file information for Windows Server 2008 R2

Additional files for all supported x64-based versions of Windows Server 2008 R2
File nameAmd64_wnetvsc.inf_31bf3856ad364e35_6.1.7600.20743_none_b3c5ff0a022bc813.manifest
File versionNot applicable
File size2,657
Date (UTC)28-Jun-2010
Time (UTC)21:57
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,895
Date (UTC)28-Jun-2010
Time (UTC)21:57
PlatformNot applicable

Article ID: 2223005 - Last Review: 05/24/2013 06:46:00 - Revision: 3.0

  • Windows Server 2008 R2 Enterprise
  • Windows Server 2008 R2 Datacenter
  • Windows Server 2008 R2 Standard
  • Windows HPC Server 2008 R2
  • kbautohotfix kbqfe kbhotfixserver kbfix kbsurveynew kbexpertiseadvanced KB2223005
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