Internet Connected, but Websites Won't Open? How to Diagnose DNS Issues

The Wi-Fi indicator shows full bars, videos are still playing, but suddenly some websites cannot be opened. Situations like this are often considered general internet issues, while the cause may be more specific: DNS.

DNS, or Domain Name System, is a service that translates names like example.com into IP addresses that computers understand. Without this process, browsers struggle to find the target server even though the internet connection is still active.

DNS issues do not always present themselves as clear messages. Browsers might display messages like “server IP address could not be found,” “DNS_PROBE_FINISHED_NXDOMAIN,” or simply keep loading the page. By recognizing the patterns, you can perform sequential checks without immediately resetting the entire network.

Differentiate DNS Issues from Internet Connection Problems

The first step is to see if all internet activities are disrupted or just access to specific domain names.

• If all websites, applications, and services are unusable, the issue may lie with the connection, modem, router, or internet service provider.
• If some websites can be opened but others fail, DNS or issues with specific domains are more likely the cause.
• If a website can be opened via its IP address but fails using the domain name, this strongly indicates a DNS issue.
• If only one device is having problems while others are normal, check the configuration of that device first.

A simple test you can perform is to open several different services, such as a search engine, news site, and email service. Don't just test one website, as the server for that website may be experiencing issues.

Start with the Safest Checks

1. Try a Different Browser or Device

Open the same website using a different browser. If the issue only occurs in one browser, the cause may be an extension, cache, or browser configuration.

You can also try another device connected to the same Wi-Fi network. If the laptop fails to open the website but the phone works fine, the issue is likely with the laptop. Conversely, if all devices exhibit similar symptoms, check the router or network DNS.

2. Turn the Connection Off and On

Activate airplane mode for a few seconds on your phone, or disconnect and reconnect the network on your computer. This forces the device to create a new network connection without permanently changing the configuration.

If using home Wi-Fi, you can restart the router. Unplug it for about 30 seconds, then plug it back in. Avoid pressing the small reset button on the router unless you are ready to reconfigure the Wi-Fi name, password, and other settings.

3. Check the Device's Date and Time

Incorrect date and time can disrupt secure HTTPS connections. Symptoms may sometimes appear as if the website cannot be opened, while the issue is not DNS-related.

Enable automatic date and time settings. After that, close and reopen the browser to repeat the test.

When to Clear the DNS Cache?

Devices typically store temporary DNS query results to speed up access to websites. This data is called the DNS cache. If a website's address changes but the device still uses the old information, access may be directed to an incorrect location.

Clearing the DNS cache can help, but it is not a cure-all for internet issues. This step is safe to perform because the system will create a new cache when the website is accessed again.

On Windows, open Command Prompt and run:

ipconfig /flushdns

If successful, Windows usually displays a message that the DNS Resolver Cache has been cleared. After that, close and reopen the browser.

On macOS, the command may vary depending on the system version. If unsure, use the network settings or official documentation for the version of macOS in use. On mobile devices, restarting the device or enabling airplane mode is usually the most practical way to refresh the network connection.

Changing DNS: When Does It Make Sense?

Routers or internet service providers typically provide DNS addresses automatically. Under certain conditions, these DNS servers may be slow, experience temporary outages, or block specific domains according to network policies.

Changing DNS to a public service can be a testing step. However, consider this a diagnosis, not a guarantee that the internet will always be faster. DNS speed only affects the process of finding the server address; once the connection is established, website performance is also influenced by server distance, network capacity, and hosting quality.

If you want to try, first note the old DNS settings. On a computer or router, you can change the automatic DNS to a trusted alternative DNS address, then retest the problematic website. If the results do not change, revert to the automatic settings and look for other causes.

Do not randomly change DNS from unclear internet lists. DNS providers can see the domain requests you send, so their reputation and privacy policies need to be considered.

Use Simple Commands to Narrow Down the Cause

Windows, macOS, and Linux users can use the nslookup command to see if a domain name successfully translates to an IP address.

nslookup example.com

If the command fails, the issue may lie with the DNS resolver being used. If it succeeds, but the browser still cannot open the website, check for other possibilities such as firewalls, proxies, VPNs, certificates, or the website server.

The ping command can also help sometimes, but the results should not be overinterpreted. Many servers disable ping responses for security, so a failed ping does not automatically mean the website is down.

If Only One Website Is Having Issues

Do not immediately change the configuration of all devices. Check if the domain can be opened from another network, such as a mobile connection. You may also wait a while if the issue is only occurring with one service.

The website may be experiencing downtime, the domain has just moved servers, or its DNS configuration has not propagated consistently. In such cases, clearing the local cache does not always resolve the issue because the problematic information may reside in the network resolver or the domain configuration itself.

What You Can Do Now

1. Test several websites and applications to see the extent of the problem.
2. Try a different browser, device, or network.
3. Check the date, time, VPN, proxy, and browser extensions.
4. Restart the connection before making permanent configuration changes.
5. Clear the DNS cache if the website has just moved or its address has changed.
6. Use nslookup to differentiate DNS issues from browser issues.
7. Note any changes made for easy reversal.

Understanding DNS makes internet troubleshooting more focused. You don't need to immediately replace the router or contact a technician every time one website fails to open. By testing devices, networks, and domain names sequentially, the source of the problem can usually be narrowed down without creating new configurations that are harder to track.

– Rio Yotto @rioyotto