Why a Free Proxy IP Is Not Working
Check an unresponsive proxy in a sensible order: address, protocol, local route, tunnel support, and the destination response.
A public list can contain an endpoint that has already stopped accepting connections. That is one common explanation for a failed proxy, but it is not the only one. The same symptom can come from the wrong protocol, a bypass setting, a blocked port, or a website refusing the exit IP.
Check the entry before changing the app
Copy the IP, port, and protocol again. A missing digit in the port or an HTTP/SOCKS mismatch is enough to prevent the handshake. Do not infer the protocol from port 8080 or 1080, and do not add a username unless the service actually supplies one.
For an HTTP endpoint, a short curl request helps keep the test separate from browser extensions and system settings:
curl --proxy http://203.0.113.10:8080 --noproxy '' --connect-timeout 5 --max-time 15 --verbose https://example.com/Replace the documentation address with your entry. For a SOCKS5 endpoint, use its actual port and the corresponding SOCKS scheme.
Look at the first failure
| Result | Likely place to investigate |
|---|---|
| Connection refused | The port is closed or a device actively rejected the connection. |
| Connection timeout | The route, filtering, or service did not complete setup within the limit. |
| Unexpected proxy handshake response | The selected protocol may not match the service. |
| 407 | The proxy wants authentication. |
| CONNECT denied | The proxy may restrict that destination or port. |
| The website returns 403 or 429 | The request reached an HTTP server, which refused or limited it. Inspect which server issued the response. |
A working TCP connection is only the first step. If the service on that port is not the proxy protocol you selected, the request can fail immediately afterward.
Use two comparisons
Try the same destination through a second proxy with the same protocol. If only the first endpoint fails during setup, that narrows the problem to that endpoint or route. Then try another ordinary destination through the first proxy. If only one website fails, investigate destination-specific policy instead of declaring the whole proxy dead.
A direct request is another useful comparison when direct access is available. Make the bypass explicit so inherited proxy variables do not quietly keep the supposedly direct test on a proxy route.
Know when to stop testing an entry
If several bounded requests fail at the same connection step, choose another entry from the free proxy list rather than increasing the wait to several minutes. Save the exact error if you need to report it. Repeatedly reconnecting does not repair a closed port or an endpoint that has been removed.
If every entry fails, step back. Check the client configuration, your network's outbound rules, and whether the destination is reachable without the proxy. A problem common to all requests is a poor reason to discard an entire list.