Fix: “Connection failed with error 691”

By: Milan Stanojevic
6 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” on Windows 10?

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 parametars

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 your email address as your username.

Solution 5 – 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 6 – 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 7 – 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 8 – 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 9 – 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 10 – 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 11 – 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 12 – 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 13 – 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 14 – 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 15 – 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.

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