There are a few things you can try to fix the “DNS server not responding” problem:

1. Restart your modem and router. This is often the simplest and most effective solution.
2. Flush your DNS cache. This will remove any outdated or corrupted information from your DNS cache.
3. Change your DNS servers. You can use public DNS servers, such as Google Public DNS or Cloudflare DNS.
4. Disable your firewall and antivirus software. These programs can sometimes interfere with DNS resolution.
5. Update your network adapter drivers. Outdated drivers can cause a variety of problems, including DNS issues.
6. Restart your computer in Safe Mode. This will start your computer with a limited set of drivers and services. If the problem does not occur in Safe Mode, then it is likely being caused by a third-party driver or service.
7. Contact your Internet service provider (ISP). If you have tried all of the above and you are still having problems, then you may need to contact your ISP.

Here are the detailed instructions on how to perform some of the above steps:

• To flush your DNS cache:

  • On Windows: Open the Command Prompt as an administrator. Type the following commands, pressing Enter after each one:

    ipconfig /flushdns
    ipconfig /registerdns
    ipconfig /renew
    

  • On macOS: Open Terminal. Type the following command, pressing Enter after:

    sudo dscacheutil -flushcache
    

• To change your DNS servers:

  • On Windows: Open the Control Panel. Click on Network and Internet. Click on Network and Sharing Center. Click on Change adapter settings. Right-click on your network adapter and select Properties. Click on Internet Protocol Version 4 (TCP/IPv4). Click on Properties. Click on the Use the following DNS server addresses radio button. Enter the following DNS server addresses:

    • Preferred DNS server: 8.8.8.8
    • Alternate DNS server: 8.8.4.4

  • On macOS: Open System Preferences. Click on Network. Select your network adapter from the list on the left. Click on Advanced. Click on the DNS tab. Click on the + button. Enter the following DNS server addresses:

    • 8.8.8.8
    • 8.8.4.4

• To disable your firewall and antivirus software:

  • On Windows: Open the Control Panel. Click on System and Security. Click on Windows Firewall. Click on Turn Windows Firewall on or off. Select the Turn off Windows Firewall (not recommended) radio button for both Private and Public networks. Click on OK.

    To disable your antivirus software, you will need to consult the documentation for your specific antivirus software.

• To update your network adapter drivers:

  • On Windows: Open Device Manager. Expand the Network adapters category. Right-click on your network adapter and select Update driver. Select Search automatically for drivers.

• To restart your computer in Safe Mode:

  • On Windows: Restart your computer. While your computer is restarting, press and hold the F8 key. When you see the Advanced Boot Options menu, select Safe Mode with Networking.

If you have tried all of the above and you are still having problems, then you may need to contact your ISP.