Fix: “Connection failed with error 691” in Windows 10

Milan Stanojevic avatar. By: Milan Stanojevic
8 minute read

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Many users use VPN in order to protect their privacy online. Although VPN tools are great, Windows 10 also supports VPN natively, so you won’t need any third-party tools in order to use it. However, issues with VPN can occur and users reported Connection failed with error 691 error message. This can be a problem if you want to use a VPN, but there are few ways to solve this issue.

How to fix “Connection failed with error 691” in Windows 10?

Table of contents:

  1. Use Microsoft CHAP Version 2
  2. Uncheck Include Windows logon domain option
  3. Change the LANMAN parametars
  4. Check if your username and password are correct
  5. Update Network drivers
  6. Check your connection’s security settings
  7. Leave domain name blank for the outside connection
  8. Use the resphone command
  9. Check if there are other active VPN connections
  10. Check your domain name
  11. Use a different Logon ID
  12. Change your username
  13. Delete and add your VPN connection
  14. Use PAP instead of LDAP
  15. Add ports to WAN/virtual server port forwarding
  16. Contact your ISP

Fix – “Connection failed with error 691”

Solution 1 – Use Microsoft CHAP Version 2

VPN uses different protocols, and in order to fix Connection failed with error 691, you need to use Microsoft CHAP Version 2. To do that, follow these steps:

  1. Press Windows Key + X to open Win + X menu. Choose Network Connections from the menu.
  2. When Network Connections window opens, locate your VPN connection, right click it and choose Properties from the menu.
  3. Navigate to the Security tab.
  4. Select Allow these protocols and check Microsoft CHAP Version 2 (MS-CHAP v2).
  5. Click OK to save changes.

After enabling Microsoft CHAP Version 2, check if the problem is the still appears.

Solution 2 – Uncheck Include Windows logon domain option

Sometimes Connection failed with error 691 message can appear if your VPN connection isn’t configured properly, but you can fix that problem by disabling Include Windows logon domain option. To fix the problem, do the following:

  1. Open Network Connections. For detailed instructions on how to do that, check the previous solution.
  2. Locate your VPN connection, right click it and choose Properties from the menu.
  3. Navigate to the Options tab and uncheck Include Windows logon domain option.
  4. Click OK to save changes.

Solution 3 – Change the LANMAN parameters

According to users, you can fix this problem on your PC simply by changing LANMAN parameters. This is relatively simple, and you can do it by following these steps:

  1. Press Windows Key + R and enter gpedit.msc. Press Enter or click OK.
  2. Local Group Policy Editor will now start. In the left pane, go to Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options.
  3. In the right pane locate and double click Network security: LAN Manager authentication level.

  4. Go to Local Security Setting tab. Choose Send LM & NTLM responses from the list. Click Apply and OK to save changes.
  5. Now double click Network Security: Minimum Session Security for NTLM SSP.
  6. Be sure to disable Require 128-bit encryption option and enable Require NTLMv2 session security option. Click Apply and OK to save changes.
  7. After making these changes, restart your PC to apply them.

Solution 4 – Check if your username and password are correct

Sometimes Connection failed with error 691 message can appear if your username or password isn’t correct. To ensure that your password is correct, we advise you to check if you have CAPS LOCK option turned on. In addition, be sure to enter your email address as your username.


Note: In order to avoid any connection errors while using a VPN, especially 691, we recommend you to switch to highly reliable VPN. We recommend Cyberghost as one of the most optimized and well-supported. It works like a charm (tested by our team) and it comes at a great price for those who want to subscribe.


Solution 5 – Update Network drivers

The next thing we’re going to try is updating your network drivers. Here’s how to do that:

  1. Go to Search, type devicemngr, and open the Device Manager.
  2. Expand Network adapters, and find your router.
  3. Right-click your router and go to Update driver. 
  4. Follow further on-screen instructions and finish installing drivers.
  5. Restart your computer.

Update drivers automatically

If you don’t want the hassle of searching for drivers on your own, you can use a tool that will do this for you automatically. Of course, as you’re not able to connect to the internet at the moment, this tool won’t be useful. However, once you get online, it will help you to keep all your drivers up to date, so you won’t be in this situation anymore.

Tweakbit’s Driver Updater (approved by Microsoft and Norton Antivirus) will help you update drivers automatically and prevent PC damage caused by installing the wrong driver versions. After several tests, our team concluded that this is the best-automatized solution.

Here is a quick guide on how to use it:

  1. Download and install TweakBit Driver Updaterdriver updater starting window

  2. For various PC problems, we recommend this tool.

    This software will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance. Fix PC issues now in 3 easy steps:

    1. Download this PC Repair Tool rated "Excellent" on TrustPilot.com.
    2. Click “Start Scan” to find Windows issues that could be causing PC problems.
    3. Click “Repair All” to fix all issues with Patented Technologies (requires upgrade).

  3. Once installed, the program will start scanning your PC for outdated drivers automatically. Driver Updater will check your installed driver versions against its cloud database of the latest versions and recommend proper updates. All you need to do is wait for the scan to complete.
    scanning proccess of Tweakbit driver updater
  4. Upon scan completion, you get a report on all problem drivers found on your PC. Review the list and see if you want to update each driver individually or all at once. To update one driver at a time, click the ‘Update driver’ link next to the driver name. Or simply click the ‘Update all’ button at the bottom to automatically install all recommended updates.
    Automatically Update complete
    Note: Some drivers need to be installed in multiple steps so you will have to hit the ‘Update’ button several times until all of its components are installed.

Solution 6 – Check your connection’s security settings

Connection failed with error 691 message can appear if your security settings aren’t properly configured. To fix this problem, you need to check your connection’s security settings by following these steps:

  1. Open Network Connections window.
  2. Locate your connection, right click it and choose Properties from the menu.
  3. Navigate to the Security tab and make sure that Typical (recommended settings) option is selected.
  4. In Validate my identity as follows section make sure that Allow unsecured password option is selected.
  5. Go to the Options tab and make sure that Include Windows logon domain option isn’t checked. Click OK to save changes.

After making the necessary changes, check if the problem is resolved.

Solution 7 – Leave domain name blank for the outside connection

Users reported that their VPN works while using the internal network, however Connection failed with error 691 appears when trying to connect to VPN via Internet connection. This is a strange problem, but it seems that solution is rather simple. According to users, they fixed the issue simply by leaving the domain name blank for the outside connection.

To fix the problem just enter your username and password and leave the domain name blank. Click the Connect button and everything should work without problems.

Solution 8 – Use the resphone command

If you have problems connecting to the VPN, you might be able to fix them by using rasphone command. You can run this command by following these steps:

  1. Press Windows Key + X and choose Command Prompt (Admin) from the menu.
  2. When Command Prompt starts, enter rasphone -d “Name of your VPN connection”.
  3. Press Enter to run the command.

Solution 9 – Check if there are other active VPN connections

Connection failed with error 691 message can appear if there are active connections. To fix this problem, be sure to check if there are any other VPN connections running. If so, be sure to disable these connections and check if that solves the problem.

Solution 10 – Check your domain name

Few users reported that this issue occurs because your domain name isn’t correct. According to users, the issue appears if your domain name uses company.local format. Users report that in order to fix the problem, you need to remove .local from the domain name. For example, if your domain name is Company.local switch it to Company and check if that fixes the problem.

Solution 11 – Use a different Logon ID

Sometimes Connection failed with error 691 message can appear if your Logon ID profile is damaged. If that’s the case, create a new Logon ID and try using it instead.

Solution 12 – Change your username

Few users reported that Connection failed with error 691 message appears due to their username. According to them, both username and password are correct, but the issue still appears. If you have the same problem, you might want to try adding domain name to your username. To do that, simply add @YourDomainName to your user name. For example, if your current username is Username, you need to change it to Username@YourDomainName. After doing that, try to connect to VPN again.

Solution 13 – Delete and add your VPN connection

If you’re getting Connection failed with error 691 message, you can fix it simply by deleting and creating your VPN connection again. This is quite simple in Windows 10, and you can do it by following these steps:

  1. Press Windows Key + I to open Settings app.
  2. When Settings app opens, go to Network & Internet section. Now navigate to the VPN tab.
  3. In the VPN section you should see all your available VPN connections. Select the connection you want to remove and click the Remove button.
  4. Now you need to add a new VPN connection. To do that, click Add a VPN connection button.
  5. After doing that, enter the necessary information to setup your VPN connection.

After creating a new VPN connection, try to connect to it and check if the issue still persists.

Solution 14 – Use PAP instead of LDAP

Users reported that you can’t use MS-CHAP v2 protocol with an LDAP server setup. By doing so, you’ll cause Connection failed with error 691 message to appear. To avoid this problem, simply switch from the LDAP server setup to PAP and the problem will be fixed.

Solution 15 – Add ports to WAN/virtual server port forwarding

This error can appear if you’re trying to use VPN in your network. According to some users, you can fix Connection failed with error 691 error message by adding ports to the WAN/virtual server port forwarding. If you’re not a network administrator, be sure to contact your network administrator and ask him to make the necessary changes.

Solution 16 – Contact your ISP

Sometimes Connection failed with error 691 message can be caused by problems with your ISP. Few users reported that the error was caused by their ISP, but after contacting the ISP the issue was resolved.

Connection failed with error 691 message can prevent you from using your VPN, and if you have this problem, we encourage you to try some of our solutions.

Editor’s Note: This post was originally published in February 2017 and has been since completely revamped and updated for freshness, accuracy, and comprehensiveness.

READ ALSO:

For various PC problems, we recommend this tool.

This software will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance. Fix PC issues now in 3 easy steps:

  1. Download this PC Repair Tool rated "Excellent" on TrustPilot.com.
  2. Click “Start Scan” to find Windows issues that could be causing PC problems.
  3. Click “Repair All” to fix all issues with Patented Technologies (requires upgrade).

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