Vista-kb18 Cisco VPN "Reason 442: Failed to enable Virtual Adapter"


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Cisco VPN problem
Cisco VPN problem

Version: 1.0.3
Difficult level: 4/5
Status: Disable ICS works well on most machines.



This KB works also for XP/Vista/Windows 7 etc. Many have emailed me telling that disable ICS (Internet Connection Sharing) fixed the problem. Cisco isn't updating their old client so this is a problem we will have until we upgrade to their newer VPN techniques.
There are many out there having problems and some might have encountered this problem?

Secure VPN Connection terminated locally by the Client.
Reason 442: Failed to enable Virtual Adapter.

Connection terminated on:


This KB describe some solutions to fix this problem, since Cisco updates the CPN client frequently it is likly that this KB will be outdated and not valid (it worked in August 2008, Cisco VPN client


You need to know at current date (September 2008) Cisco VPN client on Vista doesn't support:

  • System upgraded from Windows XP to Vista (clean OS installation required).
  • Start Before Logon
  • SmartCard Authentication
  • Integrated Firewall
  • InstallShield
  • 64bit support
  • AutoUpdate


At the time of writing this KB you must inactivate UAC, reboot, and then install Cisco VPN client, active UAC and reboot again.
When getting Cisco VPN error Reason 442: Failed to enable Virtual Adapter you have first been prompted for authentication and then a secure tunnel needs to be establish and it fails after about 60 seconds and gives you the error message. Try these solutions and in order!

Disable Internet Connection Sharing

Start by disable Internet Connection Sharing (ICS) service
Internet Connection Sharing service disabled

Try to connect with the VPN client and the error message should not show up any longer.
If this works you can stop using Internet Connection Sharing by:

  1. Click the round Start button and then select Control Panel.
  2. Click Classic View on the left side of the Control Panel.
  3. Open the Network and Sharing Center.
  4. Click Manage Network Connections on the left side of the Network and Sharing Center.
  5. Right-click the network connection you want to share and then select Properties.
  6. Select the Sharing tab at the top of the Network Connection Properties window.
  7. Check off Allow other network users to connect through this computer’s network connection.

Diagnose Virtual Adapter fix

  1. Open Network and Sharing Center
  2. Open Network Connection Manager
  3. Enable the virtual adapter (“Cisco VPN Adapter”)
  4. Right-click on it and select Diagnose


  1. Select Reset the network adapter "name of adapter"


Now wait for the reset to complete (can take up to 60 seconds or more) and then try to connect with Cisco VPN again.

Registry hack

IMPORTANT: I got a lot of feedback about this one and I cannot stress enough how important it is that you run CMD elevated as an administrator else you get "ERROR: Access is denied.", unless you have already disabled UAC

Run the following from an elevated cmd:

reg add HKLM\System\CurrentControlSet\Services\Tcpip\Parameters /v ArpRetryCount /t REG_DWORD /d 0 /f


After reboot try to connect with Cisco VPN client.


Please let me know if any of these VPN solution helped your problem by emailing me on
If you have another solution please also let me know and I will publish it here.

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