Start with the error text
Browsers show different messages for different failures, and the wording is a useful clue. Chrome adds a short code below the message, such as ERR_NAME_NOT_RESOLVED or ERR_CONNECTION_REFUSED. Firefox describes the problem in a sentence. Note the exact message before you start; it narrows the cause before you change anything.
| Message or code | What failed | First step |
|---|---|---|
DNS_PROBE_FINISHED_NXDOMAIN, “server not found” | The name could not be turned into an address | Check spelling, flush DNS |
ERR_CONNECTION_TIMED_OUT | The server did not answer in time | Run the outside check |
ERR_CONNECTION_REFUSED, “unable to connect” | The server refused the connection | Run the outside check, try later |
ERR_CONNECTION_RESET | The connection was cut during loading | Try another network, pause security software |
ERR_INTERNET_DISCONNECTED | Your device has no connection | Check Wi-Fi or cable |
ERR_CERT_DATE_INVALID and similar | Certificate could not be verified | Check the device clock |
The routine
- Run the outside check
Enter the address in the checker on the homepage. If the result is unreachable, the site is down, and waiting is the fix.
- Reload without cache
Press Ctrl+F5 on Windows or Cmd+Shift+R on a Mac to reload without stored files.
- Open a private window
If the site loads there, an extension or stored cookies are the cause. Disable extensions one at a time to find the culprit.
- Try a second browser
If another browser works, the first browser’s proxy or secure DNS setting may be wrong. Check its network settings.
- Flush the DNS cache
The DNS guide covers each system. It fixes most name-related errors.
- Switch networks
Mobile data bypasses your router, provider DNS and any network filter.
- Check security software and VPNs
Pause them one at a time and reload the page.
- Restart the router
Thirty seconds without power clears many connection problems on the home network.
Browser settings that block sites
Three settings cause most “works everywhere except here” cases. A manual proxy, often left behind by a VPN or a work configuration, sends traffic through a server that may no longer exist. Secure DNS, also called DNS over HTTPS, uses a different DNS server than the rest of your system and can fail on its own. Extensions that block ads, scripts or trackers sometimes block the parts a page needs to load. All three can be checked in the browser’s settings without touching the rest of the computer.
Network-level blocks
Schools, offices, public Wi-Fi and some providers filter sites by category or by court order. A blocked site usually shows a notice page, but some filters simply drop the connection, which looks exactly like an outage. If the outside check says reachable and the site opens on mobile data but not on a particular Wi-Fi network, a network filter is the most likely explanation.
If nothing works
When the outside check shows the site as reachable, a second browser and a second network both fail, and your device opens other sites normally, the problem may be regional: a routing issue between your provider and the site’s host. Those clear without any action on your side, usually within hours. Contacting the site’s support with your location and provider helps them find the cause faster.
When the server did answer
Not every blank or broken page is a connection failure. Chrome separates the two: “This site can’t be reached” means no usable reply came back, while “This page isn’t working” followed by HTTP ERROR 500 means the server replied and reported its own fault. Firefox and Safari draw the same line with different wording. A page that says 403 Forbidden, 429 Too Many Requests or 502 Bad Gateway belongs in the second group, too, and none of the steps above will change it, because the problem sits on the other end. The guide to HTTP status codes and what each one means for you sorts those replies into the ones worth retrying and the ones that are not.
The hosts file
One cause hides outside the browser entirely. Every operating system keeps a small text file that maps names to addresses before DNS is asked at all: on Windows it lives at C:\Windows\System32\drivers\etc\hosts, on macOS and Linux at /etc/hosts. Ad blockers, old development projects and some malware add lines to it. If a site name is pinned there to 0.0.0.0 or to an address that has since changed, every browser on that computer fails in the same way, while the same site opens on a phone without trouble. Open the file with administrator rights and look for the site’s name. Delete the line or put a # in front of it.
Then there is HSTS. A site that once told your browser to use only secure connections keeps that rule for as long as the site asked, often a full year. If its certificate breaks during that time, the warning page appears without the usual option to continue anyway. Chrome lists and deletes these stored rules at chrome://net-internals/#hsts, which is useful mainly when you run the site yourself.
Questions
What does 'This site can't be reached' mean?
The browser could not open a connection to the site. The site may be down, the name may not resolve, or something on your network may be blocking the connection. An outside check tells you which side the problem is on.
What does DNS_PROBE_FINISHED_NXDOMAIN mean?
Chrome could not find an address for the site name. Either the name is misspelled, the domain has expired, or your DNS settings are failing. Check the spelling, then flush your DNS cache.
What does ERR_CONNECTION_TIMED_OUT mean?
The browser found the server's address but got no answer in time. The site may be overloaded or down, or a firewall on your side may be dropping the connection.
Why does only one browser fail?
Each browser has its own cache, extensions, proxy and secure DNS settings. If another browser opens the site, reset or clean the failing browser rather than changing your network.
Can antivirus software block websites?
Yes. Web protection modules block sites they consider risky and sometimes block safe ones by mistake. Most show a notice; if not, pause web protection briefly to test.
Should I reset my browser?
Only as a last step. A reset removes extensions, settings and stored site data. Try a private window and a second browser first, since those tests show whether a reset is likely to help.