How to fix and resolve 'Your DNS server might be unavailable' errors on Windows 11

When you see the error message “Your DNS server might be unavailable” on a Windows 11 computer, it means your device cannot reach the Domain Name System (DNS) server it uses to translate website names (like 220.com.au) into IP addresses. This can happen after a router reboot, a network configuration change, or when your Internet Service Provider’s DNS servers are temporarily unreachable. The steps below will help you diagnose the cause and restore your internet connection.

Quick Fix Steps

Try these first. They resolve the majority of DNS errors on Windows 11.

1. Restart your computer and router. Power off your modem and router, wait 30 seconds, then power them back on. Once the router’s lights are stable, restart your Windows 11 PC.
2. Run the Windows Network Troubleshooter. Go to Settings > System > Troubleshoot > Other troubleshooters. Next to Internet Connections, click Run and follow the prompts.
3. Flush the DNS cache. Open Command Prompt as administrator and run ipconfig /flushdns. You should see “Successfully flushed the DNS Resolver Cache.”
4. Switch to a public DNS server. Temporarily set your DNS to a public service like Cloudflare (1.1.1.1 and 1.0.0.1) or Google (8.8.8.8 and 8.8.4.4). Detailed steps are in the next section.

Detailed Instructions

Check Your Current DNS Settings

1. Right-click the Start button and select Network Connections.
2. Click your active connection (usually Wi-Fi or Ethernet).
3. Click Hardware properties.
4. Look at the IPv4 DNS servers and IPv6 DNS servers entries. If they are blank or show your router’s IP address (e.g., 192.168.0.1), your computer is relying on the router to forward DNS requests.

Change Your DNS Server to a Public Provider

Using a public DNS server can bypass issues with your ISP or router.

1. Go to Settings > Network & internet > Advanced network settings.
2. Click More network adapter options.
3. Right-click your active network adapter and select Properties.
4. Select Internet Protocol Version 4 (TCP/IPv4) and click Properties.
5. Select Use the following DNS server addresses.
6. Enter 1.1.1.1 in the Preferred DNS server field and 1.0.0.1 in the Alternate DNS server field.
7. Click OK, then Close.
8. Open Command Prompt and run ipconfig /flushdns to clear any cached entries.
9. Restart your browser and test your connection.

Reset the Windows Network Stack

If changing DNS servers does not help, reset the network components that handle DNS requests.

1. Open Command Prompt as administrator. Right-click Start and select Terminal (Admin) or Command Prompt (Admin).
2. Run the following commands one at a time, pressing Enter after each:
   • ipconfig /release
   • ipconfig /renew
   • ipconfig /flushdns
   • netsh winsock reset
   • netsh int ip reset
3. Restart your computer when prompted.

Disable IPv6 Temporarily

Some routers and ISPs have incomplete IPv6 support, which can cause DNS lookups to fail even when IPv4 works correctly.

1. Go to Settings > Network & internet > Advanced network settings.
2. Click More network adapter options.
3. Right-click your active network adapter and select Properties.
4. Untick Internet Protocol Version 6 (TCP/IPv6).
5. Click OK and restart your computer.

Troubleshooting

Check If the Problem Is Your Router

1. Open Command Prompt and run nslookup 220.com.au.
2. If the command returns an IP address, your DNS is working and the issue may be browser-specific. Try clearing your browser cache or using a different browser.
3. If the command times out, run nslookup 220.com.au 1.1.1.1 to query a public DNS server directly.
4. If the second command succeeds but the first fails, your router’s DNS forwarding is faulty. Update your router’s firmware or set your computer to use a public DNS server as described above.

Check Your Hosts File

A misconfigured hosts file can override DNS lookups and cause errors.

1. Open Notepad as administrator.
2. Open the file C:\Windows\System32\drivers\etc\hosts.
3. Look for any lines that do not start with # and are not blank. If you did not add them yourself, they may be blocking or redirecting your DNS requests.
4. Add a # at the start of any suspicious line to comment it out, then save the file.
5. Run ipconfig /flushdns and test your connection.

Update Network Adapter Drivers

1. Right-click the Start button and select Device Manager.
2. Expand Network adapters.
3. Right-click your Wi-Fi or Ethernet adapter and select Update driver.
4. Choose Search automatically for drivers.
5. If no update is found, visit your computer or motherboard manufacturer’s website and download the latest network driver manually.

Check Your Wi-Fi Connection

If you are on Wi-Fi and the DNS error occurs only on that network, your wireless connection may be unstable. See How to connect to Wi-Fi for guidance on reconnecting and verifying your wireless settings.

Prevent Future DNS Errors

• Keep your router firmware up to date. Most routers have an automatic update option in their admin interface.
• Use a reliable public DNS server such as Cloudflare (1.1.1.1) or Google (8.8.8.8) on your Windows 11 device.
• Restart your router and modem at least once a month to clear stale DNS caches.
• Avoid installing third-party “internet booster” or “DNS accelerator” software, as these often interfere with Windows network settings.

If you have followed all the steps above and still see the “Your DNS server might be unavailable” error, please Open a Ticket and include a screenshot of the error message and the output of ipconfig /all from Command Prompt.