This guide covers general Cisco AnyConnect VPN issues in Windows 10, including connection failures, slow speed, and frequent disconnections.
The Cisco AnyConnect VPN client is widely used in corporate environments. With more employees working remotely, VPN access has become critical for connecting to corporate networks securely.
When Cisco AnyConnect VPN not working in Windows 10, IT help desk commonly receive complaints such as:
- Why does my VPN connection keep dropping?
- Why is my VPN connection very slow?
- Why does the VPN connection fail?
- Why is VPN not working in Windows 10?
- Can’t connect to VPN. The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer.
In some cases, users may encounter the unable to establish VPN connection error, which usually occurs due to authentication failures or incorrect VPN configuration.
If you are facing any of the above issues, follow the troubleshooting steps below to fix Cisco AnyConnect VPN problems on Windows 10.
Before applying advanced fixes, perform these basic checks:
- Check your internet speed
Make sure your internet connection is stable by running an online speed test. - Confirm VPN protocol availability with your ISP
Some ISPs block VPN protocols. Verify that the following protocols are not restricted:- Internet Protocol Security (IPSec)
- Layer 2 Tunneling Protocol (L2TP)
- Point-to-Point Tunneling Protocol (PPTP)
- SSL / TLS
- OpenVPN
- Restart your computer
If your Windows 10 system was in sleep or hibernation mode, reboot it before connecting to VPN. - Install pending Windows updates
Go to Settings → Update & Security → Windows Update and install any pending updates. - Reset your Windows password (if required)
If your organization enforces password expiration policies, ensure your password is updated.
🛠️ Cisco AnyConnect VPN Fixes (Windows 10)
Apply the following fixes one by one:
- End VPN processes
- Right-click the taskbar → Open Task Manager
- Go to Details
- End the following processes:
vpngui.exevpnui.exe
- Try a different VPN server/location
Switch to another VPN access location if available and reconnect using your Windows credentials. - Reinstall Cisco AnyConnect
- Uninstall Cisco AnyConnect VPN
- Reboot your computer
- Install the latest version of Cisco AnyConnect VPN client
- DUO / MFA authentication issues
- Ensure your mobile device has a stable internet connection
- Approve the DUO push notification immediately
- If push fails, enter your password and DUO code in this format:
MyP@ssw0rd,123456
- Antivirus interference
- If using Sophos Endpoint, temporarily disable Tamper Protection
- For other antivirus software, disable similar protection features and test VPN connectivity
⚠️ Windows Updates Causing VPN Issues (Important)
Updated as of January 2022
Microsoft released security updates that caused VPN connectivity issues on both Windows 10 and Windows 11.
Systems installed with the following updates may experience VPN failures:
- KB5009543 (Windows 10)
- KB5009566 (Windows 11)
Common error message:
“Can’t connect to VPN. The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer.”
🔄 How to Uninstall the Problematic Windows Update
- Open Control Panel
- Go to Programs → View installed updates
- Locate:
- KB5009543 (Windows 10)
- KB5009566 (Windows 11)
- Uninstall the update and restart your computer
✅ Final Notes
The above steps resolve most Cisco AnyConnect VPN connection problems in Windows 10.
If the issue persists, it may require changes on the VPN server or firewall configuration.
you can also check out Windows 10 built-in VPN client built in with Windows.
If you have discovered additional fixes, feel free to share them in the comments.
If you need assistance, contact us — we’re happy to help.
Q1. Why is Cisco AnyConnect VPN not working in Windows 10?
A: Cisco AnyConnect VPN may not work in Windows 10 due to network instability, blocked VPN protocols, outdated VPN clients, antivirus interference, or Windows update conflicts.
Q2. Why does my Cisco AnyConnect VPN connection keep dropping?
A: VPN connections may drop due to poor internet connectivity, ISP restrictions, power-saving network settings, or authentication timeout issues.
Q3. Can Windows updates cause Cisco AnyConnect VPN issues?
A: Yes. Certain Windows updates, such as KB5009543 (Windows 10) and KB5009566 (Windows 11), have been known to cause VPN connection failures.
Q4. How do I fix the L2TP VPN connection error in Windows 10?
A: The L2TP error can be fixed by uninstalling problematic Windows updates, checking IPSec services, and verifying VPN protocol and firewall settings.
Q5. Is Cisco AnyConnect compatible with Windows 11?
A: Yes. Cisco AnyConnect supports Windows 11, but only newer versions are fully compatible and stable.
Q6. Can antivirus software block Cisco AnyConnect VPN?
A: Yes. Some antivirus software with tamper protection features can block VPN traffic. Temporarily disabling these features can help diagnose the issue.