DNS translates website names into addresses. When the DNS server doesn't answer, your connection may be fine but nothing loads by name. Restarting the router and flushing DNS on the computer fixes most cases; if not, switching to a reliable public DNS server usually does.
Common causes
Router DNS has stopped responding
Most offices use the router as their DNS server. If the router hangs, DNS fails first.
Internet provider DNS outage
Provider DNS servers occasionally go down even though the internet connection itself is working.
Wrong DNS server set on the computer
A manually set DNS address from an old network, VPN, or previous IT setup can point to a server that no longer exists.
Security software or VPN interference
Some antivirus, web filters, and VPNs intercept DNS. If they malfunction, lookups fail.
Local DNS server problem
In offices with a Windows server, computers often use the server for DNS. If that server is off or its DNS service has stopped, every lookup fails.
How to fix it, step by step
- 1
Restart the router and modem
Power-cycle the modem first, then the router. This clears the most common cause.
- 2
Flush the DNS cache
Open Command Prompt and run ipconfig /flushdns. Then try the website again.
- 3
Check which DNS server the computer uses
Run ipconfig /all and look at "DNS Servers". If it lists an address that isn't your router or office server, it may be an old manual setting.
- 4
Try a public DNS server to test
In the network adapter's IPv4 settings, temporarily set DNS to 1.1.1.1 and 8.8.8.8. If websites load, the original DNS server is the problem.
- 5
Disable VPN or web filtering temporarily
Turn off VPN software or DNS filtering briefly to see whether it is causing the failure.
- 6
Reset the network stack
As a last step on Windows, run netsh winsock reset and netsh int ip reset as administrator, then restart.
When to call a technician
If your office uses a Windows server or domain, don't switch computers to public DNS — they need the internal server to find shared drives and sign in. Call us if DNS errors affect several computers, keep returning, or started after a server or router change.
On-site support across Orange County · see our business networking and WiFi installation services.
Frequently asked questions
Is it safe to change my DNS to 8.8.8.8 or 1.1.1.1?
For a standalone computer, yes. In an office with a domain or file server, changing DNS can break access to internal resources, so the fix should be made on the server or router instead.
Why does DNS stop working randomly?
Usually because the router's DNS service hangs or the provider's DNS has an outage. If it happens often, the router may need a firmware update or replacement.
Does a DNS error mean I have a virus?
Rarely. Malware can change DNS settings, but the common causes are router and provider issues. If DNS settings change by themselves, have the computer checked.