Resolving the FortiClient VPN “VPN Down” Issue: A Step-by-Step Guide

Are you having an issue where your FortiClient VPN appears to log you in using single-sign-on but once it completes, only gives the message “VPN Down”? This can be a particularly frustrating issue, especially when it only affects some users intermittently. In this blog post, I will share my journey in diagnosing and resolving this problem and provide a comprehensive guide to help you get your users back up and running.

The Problem

The issue seemed simple enough. Users were attempting to log into their FortiClient VPN using single-sign-on (SSO), and while the login process seemed to complete successfully, they were greeted with the disheartening message “VPN Down.” What made this issue particularly tricky was its inconsistency. Some users could connect without any problems, while others encountered the error.

Initial Troubleshooting

When faced with this issue, the first step I took was to ensure that the VPN settings were configured correctly. Here’s a brief rundown of the initial troubleshooting steps:

  1. Verify VPN Configuration
    • Double-check the VPN settings on both the FortiClient and the FortiGate firewall.
    • Ensure that the SSO settings are correctly configured and match the settings provided by your IT department or network administrator.
  2. Test with a Known Good Configuration
    • Use a test account and the same VPN settings to attempt a connection. This helps to rule out user-specific issues.
  3. User-Specific Checks
    • Verify that affected users have the necessary permissions and are part of the correct user groups.
    • Check for any discrepancies in user profiles that could affect the VPN connection.

Reaching Out to Fortinet Support

After exhausting the initial troubleshooting steps, I reached out to Fortinet support for further assistance. Fortinet support confirmed that the issue is not uncommon and is something they have been seeing more frequently with clients configured for SSO.

The Solution: Upgrading to FortiClient Version

The official fix for this issue, as identified by Fortinet support, is to upgrade the FortiClient software to version However, obtaining this installer is not as straightforward as downloading it from the website; it must be acquired directly from Fortinet support. Here’s how to go about it:

  1. Contact Fortinet Support
    • Open a support ticket with Fortinet to request the installer for FortiClient version
    • Provide details of the issue, including error messages and any troubleshooting steps you have already taken.
  2. Download and Install the Update
    • Once you have received the installer from Fortinet support, download it to your system.
    • Follow the installation instructions provided by Fortinet to upgrade your FortiClient software.
  3. Test the Connection
    • After upgrading, have affected users test their VPN connection to ensure that the issue is resolved.

Lessons Learned and Best Practices

Through this experience, I have learned a few key lessons and best practices that I would like to share:

  1. Keep Software Up-to-Date
    • Regularly check for updates to your VPN software and other critical applications. Staying up-to-date can help prevent and resolve issues more efficiently.
  2. Document Configuration Settings
    • Maintain detailed documentation of your VPN and network configuration settings. This can expedite troubleshooting and help in identifying any discrepancies.
  3. Utilize Support Resources
    • Don’t hesitate to reach out to vendor support when encountering persistent issues. They have the expertise and resources to help diagnose and resolve problems that may not be documented publicly.
  4. Proactive Monitoring and Alerts
    • Implement monitoring and alerting mechanisms to detect VPN connectivity issues early. This can help in addressing problems before they impact a larger number of users.


Experiencing VPN connectivity issues can be frustrating, especially when they affect users intermittently and without clear cause. However, by methodically troubleshooting the problem, reaching out to support resources, and implementing best practices, you can resolve these issues and ensure a stable VPN connection for your users. If you are facing the “VPN Down” message on FortiClient, I hope this guide has provided you with the information and steps needed to resolve the issue.

Remember, keeping your software updated and maintaining thorough documentation are key to preventing and swiftly resolving such issues in the future. If you have any further questions or need additional assistance about fixing the FortiClient “VPN Down” issue, feel free to reach out to Fortinet support or consult the FortiClient documentation for more detailed guidance.

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