It happened with many users who are using the Cisco AnyConnect Secure Mobility Client. If you are facing a “VPN failed due to unsuccessful domain name resolution” issue, then it means your Cisco clients do not establish the successful VPN connection. There is also an issue with your DNS Settings.
It is often resolved with minor DNS tweaking and establishes a VPN connection using the Cisco AnyConnect Client. Once verify from the client side that AnyConnect is properly installed and ready to use with your computer. By this, you can ensure that there is no fault from the AnyConnect Client.
Best Ways to fix the VPN connection failed due to DNS error
Method 1: Change DNS Settings
- On Windows 10, right-click on the start menu and click on Network Connections.
- Now you can see the network you are connected to, now right-click on it and go to properties.
- Now double click on Internet Protocol Version 4 (TCP/IPv4).
- A new dialog box will pop up where you need to select Obtain DNS server address automatically.
- Click Ok to save settings.
One of the primary reasons that cause VPN connection failed error because third-party VPN clients like Cisco VPN do not support static IP connections. So if You are using Google Public DNS, Open DNS, etc., you need to change it to a dynamic setting.
Method 2: Repair anyconnect.xml File
The best way to repair anyconnect.xml file is to remove this Cisco AnyConnect Client properly from your computer and reboot the PC. Then install a fresh copy of the software step by step. Finally, make ensure that it is properly installed.
Because the main problem of the “VPN connection failed due to unsuccessful domain name resolution” error is that sometimes anyconnect.xml File is corrupted and unable to make a VPN connection. You can also try to connect to another region. Maybe it can make a successful connection and repair the file.
Method 3: Reinstall Your Operating System
In the last, if the problem is not fixed by doing all the above methods, then the last possible way is to install a fresh copy of the operating system. Then, it can resolve all of your custom DNS settings, and you can install the Cisco client.
Before reinstalling Windows OS, first, take a backup of all of your important files and folders. Then you can reset or install a fresh copy of Windows OS. By doing this, you can get all the settings by default. After that, you just need to properly install the cisco client and see how it can successfully make a VPN connection.