We help IT Professionals succeed at work.

Cisco VPN Client cannot connect - Error 51

nsdhouston asked
Last Modified: 2013-08-02
I am unable to initialize the Cisco VPN client software on a Windows XP laptop.  When I click on the shortcut to intialize the program, it returns an error which reads:

"Error 51: Unable to communicate with the VPN subsystem
Please make sure that at least one network interface is active
and has an IP address and start this application again."

I have unintalled the client software and then re-installed, I have installed a newer version of the client software, and then uninstalled and re-installed the original version of the Cisco client software, and nothing has corrected this issue.

At one point in time, the client software ran perfectly on this laptop.  Without any knowledge of any changes to the system, it just started this error message a week ago and I cannot get around it.

Please advise on this - it is a critical issue dealing with a local law enforcement agency.
Watch Question

Normally you would be right on track - more times than not, "VPN Subsystem" problems have to do with the vpn client software not properly communicating with the operating system.  Don't know if you're dealing with a "windows thing" or an environmental issue - firewall, etc.   Any software firewalls configured on the box that might be doing something weird? Any changes made to the system that you can tell us about?



Well, I gave up on this issue and decided to reload the laptop altogether.

I never was able to identify why the system started randomly having this problem and I experienced several other software related issues as I continued to troubleshoot the problem.

At the end of the day, it was easier to just reload the system and start from scratch.
This one is on us!
(Get your first solution completely free - no credit card required)

I have more or less the same problem.
Error 51 while I start the vpn client.
I have tried: Reinstallation, upgrade, downgrade, registry clean with WinTools.net Pro, TCPSock reset.

Helps nothing...

Cisco VPN Client cannot connect - Error 51 any help

If you have McAfee firewall installed remove it. this is casued by third partry firewall.
Rajah - HORIBA
Thanks @ HoribaIT as a full reinstall of the OS was not required.

Gain unlimited access to on-demand training courses with an Experts Exchange subscription.

Get Access
Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Empower Your Career
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE

Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

  • Troubleshooting
  • Research
  • Professional Opinions
Unlock the solution to this question.
Join our community and discover your potential

Experts Exchange is the only place where you can interact directly with leading experts in the technology field. Become a member today and access the collective knowledge of thousands of technology experts.

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.