Open the site on another device on the same network, then on your own device via mobile data. If it is unavailable on both networks while other sites work, a site outage is likely. If it works via mobile data, check your home network and provider. If the problem only affects one device, start with the browser. For a step-by-step list of fixes, see what to do if the problem only affects you.
How to compare devices and networks without drawing a false conclusion
- Check the address: correct any typos and refresh the page. Open several other sites. If many of them fail, check your internet connection.
- Take another device: connect a phone or laptop to the same Wi-Fi network and open the same address. If it works there, the cause is probably the first device.
- Change networks: on the phone, turn off Wi-Fi and repeat the test via mobile data. Simply switching browsers keeps you on the same network and does not test the path through another operator.
- Compare browsers: on the problem device, open the site in a different browser. In Chrome, try Menu → New incognito window. If the page loads there, check the extensions and saved data of your regular profile.
Incognito mode helps narrow the search down to the browser profile: extensions, the cache (temporarily stored data) and other site data.
| What you see | Likely cause | What to do and who fixes it |
|---|---|---|
| The site does not open on different networks, other sites work | Outage of the site or its infrastructure | Check the official status page; the site's team fixes it |
| Works via mobile data, but not at home | Router, network settings or the path through the provider | Restart your router; then contact the provider |
| Failure only on one device | Browser, settings or security software | Check the device using the main guide |
| Works in incognito, but not in a regular window | Profile data or extensions | Check extensions and the data for that particular site |
Opening the site via mobile data shows dependence on the network. Blocking by the provider is possible, but this test does not prove it: similar results are produced by routing errors and DNS (the domain name system), which translates a site's name into a network address.
How to compare devices and networks without drawing a false conclusion
Open the site on another device on the same network, then on your own device via mobile data.
Where to confirm a widespread outage
Look at the official service status page and its social media accounts. Check the time of the post and the affected feature: an outage of account sign-in does not necessarily mean the whole site is down.
Third-party "is it down" checkers give an additional signal. Such a service contacts the site from its own servers and its own region. A successful check from there does not rule out a problem for users in your region, and a single failed request does not prove a widespread outage.
What ping shows in Windows
If comparing networks has not given a clear answer, check whether the address is reachable. In Windows, open Start → Search → Command Prompt. In the commands, replace the placeholders in angle brackets with your own values and remove the brackets themselves. Enter the domain without the protocol and without the page path.
ping <domain>Then check the known IP address (the numeric address of a host) of the same site. You can obtain it using nslookup from the next section, if the query returns an answer.
ping <IP address>If the address responds, but Windows cannot find the host when querying by name, a name resolution problem is likely. If the name has already been resolved to an address but no replies come back, this on its own does not point to DNS. It is precisely this distinction that the ping command helps you check.
Note: ping sends ICMP service messages (the Internet Control Message Protocol). The server or the network may filter them, so the absence of a reply does not prove that the website is down. A successful reply also does not verify that the page works.
How to compare DNS responses in Windows
In the same command prompt, query the default DNS server:
nslookup <domain>Then query the same domain against Google's public DNS server:
nslookup <domain> 8.8.8.8The second command does not change Windows settings. Look at the answer for the domain: the address at the start of the output may belong to the DNS server itself.
| Message | What it means |
|---|---|
| Nonexistent domain | The server reports that such a name does not exist |
| timed out | No response arrived within the allotted time |
| Server failure | The DNS server could not return a valid response due to an internal error |
| Refused | The DNS server refused to serve the request |
These are the values from Microsoft's nslookup documentation. If the responses differ, keep both results for your provider or administrator. The difference on its own does not prove blocking.
Why 503, 504 and 522 point to the site's side
HTTP (the protocol for exchanging web requests and responses) carries a code indicating the result of the request. If you see a page with such a code, a server or an intermediate node has already responded.
- 503: the server is temporarily not ready to process the request, for example due to overload or maintenance. Usually all that remains is to wait for recovery.
- 504: a gateway or proxy — that is, an intermediary between you and the server — did not receive a response from the next server in time. This is normally fixed by administrators.
- 522 on a Cloudflare page: the CDN (content delivery network), which serves visitors in front of the site's server, did not receive a response from that server in time. The fix is the responsibility of the site owner or the host, as explained in Cloudflare's documentation.
There is an exception for 504: if the site works for others, and you have a VPN (virtual private network) or an unusual network configuration enabled, check your own settings, proxy, firewall and DNS. This is specifically noted in the MDN documentation.
The browser errors ERR_CONNECTION_TIMED_OUT, ERR_CONNECTION_RESET and ERR_CONNECTION_REFUSED mean a connection timing out, being reset and being refused respectively. They do not identify the culprit. If the connection drops only on this network, use the breakdown of the timeout and connection reset variants.
Frequently asked questions about test results
What should I do about the Nonexistent domain message?
First check the spelling of the domain: the DNS server reports that no such name exists. Compare the response with a public server. If the responses differ, the problem may lie with the DNS you are using, so it is too early to delete browser data.
The name resolves via 8.8.8.8 but not via my DNS. What next?
The problem probably lies with the default DNS server or with access to it. On a home network, you can temporarily change the DNS following the main guide, after writing down the previous settings. On a work network, pass the results to the administrator.
Will a VPN help if the site is down for everyone?
No: changing the route will not start a stopped server or remove its overload. Once an outage is confirmed, follow the official status page and wait for recovery.
For details about CitadelVPN itself, see the CitadelVPN website.
When to wait and when to fix your connection
If the site is unavailable on different networks, other pages work and the official status page confirms an outage, wait for the service to fix it. If the problem only affects one device, move on to checking the browser and network settings.
If the site works via mobile data but is unavailable at home on several devices, switch off your router and modem for at least 30 seconds, then switch them back on and wait for them to start up. If that does not help, pass the site's address, the error code and the results of your network comparison to the provider. On a work, school or college network, contact the administrator.