3 Fixes For The VPN Connection Failed Due To Unsuccessful Domain Name Resolution

A crucial and private phone call. Online exchange of sensitive information. In these anxious and stressful circumstances, you need everything to be secure and secure, which is why you make use of a VPN. Then, an “the VPN connection failed due to unsuccessful domain name resolution” error occurs. It sounds awful? You could get even more If you’re connected to a country with internet restrictions and a low Internet Freedom Index.

Introduction to VPN

A VPN is an encrypted connection that can be established between the computer and a secured corporate network and an unsafe open system. Information that is transferred via the public network is then encapsulated and then encrypted to make sure that it isn’t able to be altered or intercepted.

the VPN connection failed due to unsuccessful domain name resolution

The process of passing data over a network but not allowing the networks to view the data in this manner is called tunneling. In essence, the connection operates as if the device were connected to the secure network via its own private cable using a unidirectional point-to-point connection. This is why the name VPN means the virtual private network.

What is the cause of the VPN connection failed due to unsuccessful domain name resolution with fixation?

VPNs can slow your internet connection; however, they shouldn’t cause an extreme decrease in speed. If you’re experiencing a connection that’s poor and you find it hard to access websites, it’s the right time to act.

Utilize a fast, premium VPN

If you’re using a free VPN, it’s almost guaranteed to experience slow speeds with your connection. It’s normal that VPN providers are more concerned about paying customers. Although they may claim that the free VPN is as efficient as their premium service, it is possible that you don’t agree.

There are many affordable VPNs that offer high speeds and, if you’ve not yet made the switch, we strongly recommend you do so. It is possible that your speed will rise immediately.

Use appropriate Servers

The server you connect to in your VPN connection will have a significant impact on the speed of connection you receive. As close as you can get to the site, you’re connecting to the faster speeds you’ll experience (in most cases). It is possible to get faster speeds on servers that aren’t used by as many people.

Change Servers

The majority of VPN clients allow users to switch servers. Open the client, choose the server you want to switch to, and then confirm the selection. Then, you can run the speed test or browse to see whether this new server will be operating more efficiently.

If you use a VPN via your router, the procedure may be more difficult and could differ in accordance with your specific VPN provider. If you are able to recall the procedure you followed to set up your router VPN; it is possible to use your router’s settings to alter the server that you connect to.

If you’re not sure of the procedure or if anything has changed, refer to the manuals of users for the firmware of your router and your VPN.

Remote desktop connection resolution too small, Analyze The Ports

Your computer’s connection to the VPN server is made through a networking port in your computer. It is possible to think of this port in the same way as it is a physical port.

Your computer redirects traffic through your VPN server onto a particular port and traffic coming from different locations to ports. It assists in keeping all traffic from different sources in one.

Change Ports

If you think every port is equally quick as the other, you could be surprised to learn that switching the port that your VPN is connecting to will assist. Certain ISPs have a tendency to slow down traffic on certain ports, and you may discover that certain ports are more speedy than others without any apparent reason. Switch your VPN connection to various ports to determine which ones are the fastest.

Change IP Protocols

Changing IP Protocols

The majority of VPNs permit you to connect through Transmission Control Protocol (TCP) or User Datagram Protocol (UDP). Switching between the two options can allow you to achieve faster speeds, particularly when you’re switching to TCP in favor of UDP. Be aware of poor-quality connections, however.


TCP is the most commonly used on the Internet because it has error correction features and error correction, so in the event of an issue with the connection or if some of the data has been damaged, the transmission is still successful, and the sending machine is able to redo the message if it was not received correctly.


UDP is, although not as popular, is significantly quicker than TCP. It doesn’t offer error correction, which means that when something goes missing in transit, it can’t send the data back. This reduces the amount of time needed to transfer data. However, it can also cause a weaker connection.

Change VPN Tunneling Protocols

Although OpenVPN is generally thought to be the most suitable protocol for VPN traffic, However, there are instances when you might need to make use of L2TP/IPSec. Although it’s not as secure and doesn’t offer the same security, and doesn’t offer as many features, it’s likely that it gets slipped through filters that slow OpenVPN traffic.

When you’re using the VPN to protect your privacy or security, we do not suggest using L2TP/IPSec unless you are able to stop it. If you’re simply trying to overcome the restrictions on your region, it might be able to work. However, it’s not as secure.

Disable Local Security Software

It’s not something we would recommend in a hurry, and if you are able to avoid it, you ought to. However, if your antivirus is checking all of the outbound messages you send, it may be slowing your connection. Try disabling it for a while to determine how it affects the speed of your connection.

What are some ways to resolve VPN connection problems caused by DNS errors?

  1. Change your DNS Settings
  2. Repair the anyconnect.xml file
  3. Reinstall your operating system

Method 1: Change Your DNS Settings

  • Modify your DNS settings
  • For Windows 10, right-click the Start button.
  • Click on Network Connections > Change adapter options.
Network Connections > Change adapter options
  • Right-click the network adapter and then select Properties.
  • Double-click Internet Protocol Version 4 (TCP/IPv4).
IPV4 section in the Network settings
  • Select the DNS server address to be obtained automatically.
Obtain DNS server address automatically radio button
  • Click OK.

The DNS error could be caused by customized DNS settings, like Google Public DNS, OpenDNS, or Cloudflare. In some instances, static DNS servers aren’t suitable for VPN clients such as Cisco VPN.

But, you can solve this problem by setting your computer’s DNS settings back to default settings, which is to use the DNS servers offered through your ISP. If the issue persists, then you must call your ISP.

If the DNS servers of your ISP aren’t working as they should, and that’s the real reason you chose to use custom DNS initially, You should consider using different static DNS servers.

Method 2: Repair the anyconnect.xml file

In certain cases, it is possible that AnyConnect’s XML profiles can become corrupted and the VPN connection to fail due to an error of domain name resolution not working. But, it is possible to resolve this issue by restarting AnyConnect.

Try connecting to another area, using a different VPN connection, and by checking for the DNS names and the port inside the XML file to determine whether the information is correct.

Method 3: Reinstall your operating system

If your VPN connection fails because of an ineffective DNS resolution issue with the methods above, make backups of all your important files and applications for the purpose of reinstalling Windows 10.

This method ensures that all system settings will be restored to their default. You can also use the Refresh Tool to create a fresh installation.

In conclusion, the options offered above are enough to repair the VPN issue caused by an unresolved domain name resolution error when using Cisco AnyConnect on your Windows PC.

If the problem persists, think about switching off Cisco VPN and replacing it with another VPN solution for corporate use.


This “VPN Authentication Failed” error is not uncommon. However, the fix is easy. With these tips, you’ll soon browse safely again. We hope that this article has helped you.