How to Fix Teredo is Unable to Qualify

  • Blog
  • September 22, 2022

If you’re getting the “Teredo is unable to qualify” error on your Windows 10 computer, don’t worry. You can fix it with a few simple steps. Here’s what you need to do:

How to Fix Teredo is Unable to Qualify

What is Teredo?

Teredo is a networking protocol used to tunnel IPv6 traffic over an IPv4 network. It is often used in scenarios where direct communication between IPv6 and IPv4 hosts is not possible, such as when an IPv6 host is located behind a NAT device.

When Teredo is unable to qualify, it means that it is unable to establish a connection with a Teredo server. This can be caused by a number of factors, such as a firewall blocking Teredo traffic, or the Teredo server itself being unavailable.

To fix this issue, you will need to ensure that Teredo traffic is not being blocked by your firewall, and that the Teredo server is accessible. You can do this by opening port 3544 on your firewall, and checking the status of the Teredo server using the “ipconfig /all” command.

Why is Teredo Unable to Qualify?

There are a few reasons why Teredo might be unable to qualify. One reason could be that your computer’s firewall is blocking Teredo traffic. To fix this, you’ll need to add an exception for Teredo in your firewall settings.

Another reason could be that you’re behind a NAT device that’s not configured correctly. To fix this, you’ll need to make sure that your NAT device is allowing Teredo traffic through.

Finally, Teredo might be unable to qualify if you’re using a VPN. This is because Teredo only works with public IP addresses, and VPNs typically use private IP addresses. To fix this, you’ll need to disable your VPN while using Teredo.

How to Fix Teredo is Unable to Qualify?

If you’re seeing the “Teredo is Unable to Qualify” error, it means that your computer is unable to connect to the Teredo tunneling protocol. This can be caused by a number of factors, including firewalls, anti-virus software, and incorrect network settings.

There are a few things you can try to fix this issue:

1. Check your firewall settings.

Make sure that your firewall is not blocking Teredo traffic. You can do this by checking the firewall settings in your control panel.

2. Temporarily disable your anti-virus software.

Your anti-virus software may be blocking Teredo traffic. Try temporarily disabling your anti-virus software to see if that fixes the issue.

3. Change your network settings.

If you’re using a VPN or proxy, try disabling it. You can also try changing your DNS settings to public DNS servers.

4. Reinstall the Teredo adapter.

If none of the above solutions work, you can try reinstalling the Teredo adapter. To do this, go to Control Panel > Network and Internet > Network Connections. Right-click on the Teredo adapter and select “Delete”.

Restart your computer and the Teredo adapter should be automatically reinstalled. If it’s still not working, you can try manually installing the Teredo adapter by following the instructions here:


If you’re still having trouble after following the steps above, you may need to perform a clean reinstall of Windows. This will delete all your files, so make sure to backup anything important first. Once you’ve reinstalled, follow the steps above again to set up Teredo.

How to Fix Teredo is Unable to Qualify

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