How to resolve VPN Error 691 on Windows 10?

By ivan.diskin | November 21, 2019 |

greater than 5 minutes

A Virtual Private Network (VPN) is an encrypted tunnel that protects your privacy while online. Think of it as software that masks your online activities from prying eyes, such as the government or your company administrator. In other words, when you use a VPN to connect to the internet, your connection is secure and private and no one can access your internet data. VPN software comes in especially handy if you’re using public Wi-Fi to send sensitive information or if you want to keep your browsing history to yourself.

While a VPN serves an important purpose, it’s not unusual for it to run into issues. Some Windows users reported getting “Error 691” while trying to connect to the VPN. The error prevents you from accessing the internet, which can be quite annoying. In today’s Windows tutorial, you’ll learn how to resolve Windows VPN Error 691 and what triggered the error in the first place.

What Is VPN Error 691?

The VPN Error 691 usually occurs when the client device fails to connect to the server. The error message reads in full:

“Error 691: The remote connection was denied because the user name and password combination you provided is not recognized, or the selected authentication protocol you selected is not permitted on the remote access server.”

It means that the authenticity of the connection could not be confirmed by the client server. The error can be triggered by one or more of the following:

  • entering incorrect credentials (username and password)
  • incorrect network settings
  • using two VPN clients on the same computer
  • wrongly configured connection security settings
  • Windows Firewall or your third-party antivirus program blocking the VPN
  • trying to log in to the VPN using the wrong domain

How to Fix VPN Connection Failed with Error 691?

Have you confirmed that you’re using the correct username and password? If not, then this simple fix could help you get rid of the VPN Error 691. Additionally, if you have two VPNs installed on the same PC, they could be conflicting with each other. Try disabling one of the VPNs and check if the issue goes away. If the error persists, try the solutions below one after the other until you resolve your issue.

Fix 1: Diagnose Your VPN Connection

Start by diagnosing your VPN connection to try and identify what the problem could be. Windows will try to detect and fix the issue for you. To do so, follow the steps below:

  1. Bring up the Quick Link menu using the Win + X shortcut.
  2. Select “Network Connections” and locate your VPN connection.
  3. Right-click on it and select “Diagnose”. Windows will initiate the scan and try to fix the issue.
  4. If Windows doesn’t resolve the error or doesn’t find any issues, right-click your VPN connection again and select “Disable”.
  5. Wait a few seconds and then re-enable your VPN connection.

Now, go ahead and check if the problem has been fixed. If not, try the next fix.

Fix 2: Allow Microsoft CHAP Version 2 (MS-CHAP v2)

The VPN Error 691 can be resolved by changing the protocol that the VPN uses to Microsoft CHAP Version 2 (MS-CHAP v2). Here’s how to proceed:

  1. Open the “Run” dialog box using the Win + R shortcut.
  2. Type in cpl and press “Enter”. This command takes you directly to the “Network Connections” window in “Control Panel”.
  3. Find your VPN connection, right-click it, and select “Properties”.
  4. Switch to the “Security” tab, and check the radio button next to “Allow these protocols”.
  5. Check “Microsoft CHAP Version 2 (MS-CHAP v2)”.
  6. Click “OK”.

Check if this fix resolves the VPN Error 691.

Fix 3: Uncheck the “Include Windows logon domain” Option

If you’re attempting to log in to your VPN with a domain that’s not allowed, then you might encounter Error 691. To fix this, you need to uncheck “Include Windows logon domain” in your VPN’s dialing options. Here’s how to go about it:

  1. Press Win + R, type in cpl, and click “OK” or press “Enter”.
  2. Right-click your VPN connection and select “Properties”.
  3. Navigate to the “Options” tab and uncheck the “Include Windows logon domain” option.
  4. Click “OK” to save the changes.

Now check if you’re still getting the VPN Error 691.

Fix 4: Change LANMAN Parameters

According to several users, changing LANMAN parameters resolved the VPN Error 691. To check if it works for you, follow the steps below:

  1. Launch the “Run” dialog using the Win + R keyboard shortcut.
  2. Type msc and press “Enter”.
  3. In the “Local Group Policy Editor” window, go to this path:
    • Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options
  4. Find “Network security: LAN Manager authentication level” in the right pane and double-click it.
  5. In the “Local Security Settings” tab, click the drop-down menu and select “Send LM & NTLM responses”.
  6. Next, find “Network security: Minimum session security for NTLM SSP based (Including secure RPC clients)” and double-click on it.
  7. Uncheck “Require 128-bit encryption”.
  8. Click Apply > OK to save the changes.

Restart your machine and check if the VPN Error 691 has been fixed. If not, don’t despair. Move on to the next solution below.

Fix 5: Re-Configure Your Connection Security Settings

If your connection security settings are wrongly configured, it could lead to the VPN Error 691 on your Windows 10 PC. To check if your connection security settings are configured properly, follow the guide below:

  1. Open the “Network Connections” window in “Control Panel”. To do so, press the Windows Key and R together, type in cpl and press “Enter”.
  2. Right-click your VPN connection and select “Properties”.
  3. Switch to the “Security” tab and make sure that the “Typical (recommended settings)” option is selected. If not, click on it to select it.
  4. In the “Validate my identity as follows” section, select the “Allow unsecured password” option if it’s not already selected.
  5. Next, switch to the “Options” tab and uncheck “Include Windows logon domain”.
  6. Click “OK” to save the changes and reboot Windows.

Now try connecting to the internet via your VPN, and hopefully, the error should be fixed.

Protect Your Computer from Viruses

While VPNs create a safe browsing environment, there is a misconception that they also protect from malware. Well, this information is inaccurate. VPNs operate quite differently from malware removal tools in that they keep your data private and safe from hackers. However, they don’t protect against computer viruses and other malware. Nowadays, cybercriminals use many forms of malicious software to invade PCs and steal sensitive information which they can use against you.

On the same note, some free VPNs are actually developed by hackers to trick you into thinking that your information is safe and encrypted, while in actual sense, the attackers are siphoning all of your data.

For this reason, you need an advanced malware removal tool like Auslogics Anti-Malware to thwart their efforts to steal sensitive data from your computer. The tool offers an additional layer of security on your Windows device and doesn’t conflict with your antivirus program or Windows Defender. This security program defends your PC from malware by identifying any forms of suspicious apps or processes and stopping them before they inject themselves into your system. Auslogics Anti-Malware is a powerful security tool that, if paired with a reliable VPN, provides you with maximum online protection.

VPN errors can leave you frustrated since accessing the internet becomes a nightmare. We hope you could resolve the Windows VPN Error 691 using our solutions. If the error persists, contact your VPN provider for more assistance.

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