DNS problems explained

DNS is like the internet's phone book. It turns website names such as a shop or bank address into the numbers computers use. If DNS stops working, you may be connected to Wi-Fi but see errors saying a site cannot be found.

Signs of a DNS problem

• Websites will not open, but apps still work.
• Messages such as "server not found" or "DNS probe finished".
• Some sites work and others do not.
• Typing a numeric address works, but a name does not.

Try this first

1. Restart the router properly: off for 30 seconds, then on.
2. Restart the device.
3. Try another device to see whether it is just one.

Trying a different DNS service on one device

Your router normally hands out your provider's DNS. You can test whether it is at fault by using a public one on a single device. Popular choices are 1.1.1.1 and 8.8.8.8. Menus vary by device, so look for the Wi-Fi network settings and a section called DNS or IP settings.

1. Open the Wi-Fi settings on the device.
2. Choose your network and look for Advanced, Configure DNS or IP settings.
3. Change DNS from Automatic to Manual.
4. Enter 1.1.1.1 and 8.8.8.8 as the two DNS addresses.
5. Save and try the website again.

If it now works, the DNS from your router or provider is the likely cause. You can leave the device like that or set it back to Automatic later.

Be careful

• Only change this on one device while testing, not everywhere.
• Write down the original settings first.
• Public DNS services are run by companies, and your lookups go through them, so choose one you trust.
• Do not change router-wide settings you do not understand.

Clearing the cache

Devices remember old DNS answers. On Windows, restarting usually clears it. Turning a phone's Wi-Fi off and on, or restarting it, does the same.

When to get more help

If changing DNS does not fix it, or a site is blocked on every device, tell us which sites fail and we will investigate.