DNS Server Unavailable? Fix It in 8 Steps

If you see a “DNS server unavailable” error, your device cannot reach the domain name system, so it can’t translate website names like example.com into IP addresses. This usually means your router, your ISP, or a public DNS server is temporarily unreachable, and you can fix it by restarting your network hardware, switching DNS servers, or flushing your DNS cache. Below is a step-by-step guide to diagnose and resolve the issue on Windows, macOS, Android, and iOS.

What Causes the “DNS Server Unavailable” Error?

The DNS (Domain Name System) acts like the internet’s phone book. When you type a web address, your device asks a DNS server for the correct IP address. If that server doesn’t respond, you get an error like “DNS server unavailable,” “DNS_PROBE_FINISHED_NXDOMAIN,” or “Server IP address could not be found.” Common triggers include:

• Router or modem glitches — temporary firmware hangs or overheating.
• ISP outages — your provider’s DNS servers are down or overloaded.
• Incorrect DNS settings — a manually configured server that no longer works.
• Firewall or antivirus interference — security software blocking DNS queries.
• Corrupted local DNS cache — stale or bad entries on your device.
• VPN or proxy conflicts — a VPN that fails to route DNS traffic properly.

Diagnosing which of these applies is the first step to a permanent fix.

Step 1: Restart Your Router and Modem

This clears temporary glitches and re-establishes the connection to your ISP. Unplug the power from both the modem and the router (if separate). Wait 30 seconds, plug the modem back in, wait for it to fully boot (lights stabilize), then plug in the router. Once both are online, restart your computer or toggle Wi-Fi off and on. This fixes roughly 40% of DNS errors because it forces your router to renew its DHCP lease and re-fetch DNS server addresses.

Step 2: Flush Your DNS Cache

Your device stores previous DNS lookups to speed up browsing. If a cached entry is corrupt or outdated, you can get a false “unavailable” error. To clear it:

1. Windows: Open Command Prompt as administrator and type ipconfig /flushdns.
2. macOS: Open Terminal and type sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder (on newer versions).
3. Android/iOS: Toggle Airplane Mode on for 10 seconds, then off. This clears the temporary cache without erasing your data.

After flushing, try loading a website. If the error persists, move to the next step.

Step 3: Switch to a Public DNS Server

Your ISP’s DNS servers may be unreliable. You can manually set your device to use a well-known public resolver. Two widely used options are:

• Google Public DNS: Primary 8.8.8.8, Secondary 8.8.4.4
• Cloudflare DNS: Primary 1.1.1.1, Secondary 1.0.0.1

To change it on Windows: go to Control Panel > Network and Sharing Center > Change adapter settings, right-click your connection, select Properties, choose “Internet Protocol Version 4 (TCP/IPv4)”, and enter the addresses. On macOS: System Settings > Network > your connection > Details > DNS, then add the addresses. On a router, log into its admin page (usually 192.168.1.1 or 192.168.0.1) and look for DNS settings under WAN or Internet. Changing it at the router level fixes all devices at once.

Step 4: Disable VPN and Proxy Settings

VPNs and proxies route your DNS queries through their own servers. If that server is slow or blocked, you’ll see the error. Temporarily disconnect your VPN and try browsing. On Windows, check that no proxy is enabled: Settings > Network & Internet > Proxy, and turn off “Use a proxy server.” On macOS, check System Settings > Network > Proxies. If the error disappears, reconfigure your VPN’s DNS settings or choose a different server location.

Step 5: Check Firewall and Antivirus Settings

Some security suites block DNS queries to “protect” you, but they can mistakenly block legitimate traffic. Temporarily disable your firewall or antivirus and test. If the error goes away, add an exception for your browser or for the DNS service (port 53). Remember to re-enable your security software afterward. On Windows, you can also check if the built-in Defender Firewall is blocking “Core Networking – DNS” by going to Windows Defender Firewall > Advanced Settings > Inbound Rules and ensuring the DNS rule is enabled.

Step 6: Renew Your IP Address

A stale IP lease can cause DNS failures. On Windows, open Command Prompt as administrator and run:

ipconfig /release
ipconfig /renew

On macOS, go to System Settings > Network > your connection > Details > TCP/IP, and click “Renew DHCP Lease.” On Android, go to Wi-Fi settings, tap your network, and choose “Forget” then reconnect. This forces your device to request a fresh IP and DNS configuration from the router.

Step 7: Disable IPv6 (Temporarily)

Some networks have broken IPv6 configurations. If your device tries to use IPv6 DNS and fails, it may not fall back to IPv4. To test, disable IPv6 on your adapter:

• Windows: In the adapter properties (same place as step 3), uncheck “Internet Protocol Version 6 (TCP/IPv6)” and click OK.
• macOS: System Settings > Network > Details > TCP/IP, change “Configure IPv6” to “Off.”

If the error resolves, you can leave it off or investigate your router’s IPv6 settings. Many users never need IPv6, so this is a safe permanent fix for most home networks.

Step 8: Reset Network Settings (Last Resort)

If nothing else works, reset all network configurations to factory defaults. This clears any corrupted settings but also removes saved Wi-Fi passwords and VPN profiles.

• Windows: Settings > Network & Internet > Advanced network settings > Network reset, then click “Reset now.”
• macOS: Delete the network service and re-add it (System Settings > Network > the connection > “-”), then create a new one.
• Android: Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth.
• iOS: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.

After resetting, reconnect to your Wi-Fi and test. This usually resolves persistent DNS errors caused by misconfigured profiles.

Frequently Asked Questions

Why does the error say “DNS server not responding” on Windows but works on my phone?

This usually means the Windows network adapter has a stale DNS setting or the firewall is blocking it. Try flushing the DNS cache and resetting the adapter (step 6). If your phone works, the problem is local to your PC, not your router or ISP.

Can I use 8.8.8.8 permanently?

Yes, Google Public DNS is free and reliable for most users. It supports DNSSEC and is available worldwide. Some ISPs block direct access to external DNS, but that is rare. If you notice slower speeds, switch back to your ISP’s DNS or try Cloudflare’s 1.1.1.1.

What does “DNS_PROBE_FINISHED_NXDOMAIN” mean?

This Chrome-specific error means the DNS server responded, but the domain does not exist. It often indicates a typo in the address or a site that has been taken down. However, it can also appear if your DNS cache has a stale entry — flush the cache and try again.

Is it safe to change DNS servers?

Yes, using a reputable public DNS like Google or Cloudflare is safe and often improves privacy (they do not sell your browsing history, though they do log some data). Avoid unknown third-party DNS servers advertised on forums, as they could be malicious. Always verify the IP addresses from the official provider website.

Why does the error happen only on one device?

If only one device fails, the problem is local to that device — check its DNS settings, firewall, VPN, or IPv6 configuration. Other devices on the same network are unaffected because they use the router’s DNS settings, which are working correctly.

Can a router firmware update fix DNS errors?

Yes, router firmware updates often fix bugs related to DNS forwarding and DHCP. Check your router manufacturer’s support page for the latest firmware. If the router is more than 5 years old, consider replacing it, as older models may not handle modern DNS-over-HTTPS or IPv6 correctly.

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