Proxy not working? Start with the failing connection
Troubleshoot proxy connection failures, 407 errors, timeouts and location mismatches. Follow a clear diagnosis path and collect useful evidence for support.
Start with the exact error and a single request. Check whether the client reaches the proxy, whether authentication succeeds, and whether the failure affects every destination. Follow the matching guide below before changing the rental or rotating its IP.
Choose the symptom you see
Keep one client, one proxy endpoint and one test URL while you investigate. Changing several settings together makes it difficult to tell which change helped. Use a small HTTPS page you are authorized to request.
| What you see | First useful check |
|---|---|
| ERR_PROXY_CONNECTION_FAILED | Check the proxy host, port and active browser settings. |
| ERR_TUNNEL_CONNECTION_FAILED | Read the HTTP proxy CONNECT response. |
| 407 Proxy Authentication Required | Check the proxy credentials and authentication method. |
| A connection or read timeout | Identify which operation reached its time limit. |
| Only one website fails | Compare a neutral request with the affected destination. |
- Fix ERR_PROXY_CONNECTION_FAILED in Chrome
- Resolve a 407 proxy authentication error
- Diagnose a proxy timeout
- Diagnose a failed CONNECT tunnel
- Check Chrome SOCKS5 authentication support
References: Chromium network errors; MDN: proxy authentication response
The connection works, but the result is wrong
A page loading successfully does not prove that the intended proxy carried the request. Confirm the exit IP inside the affected browser or application. Then check the result you care about: country, response content or elapsed time. A test run from another machine follows a different network path.
Separate a proxy failure from a website response
If a neutral request succeeds and the application fails, compare their status codes and response headers. Check whether the proxy returned an error during CONNECT or the website returned it after the tunnel opened. Keep the hostname and timestamp with the result so support can reproduce the same request.
A successful HTTP CONNECT tunnel is one step in an HTTPS request. The destination can still reject a later request. Treat a Chrome tunnel error, an HTTP status and a client timeout as separate observations.
References: curl proxy and configuration options
Check the rental before changing the device
Confirm that the rental is active and that your client uses its current connection details. The public website, portal login and proxy endpoint serve different purposes. Use the issued proxy host and port in your client.
If the connection stopped around expiry, check the renewal process. If it stopped during an IP change, record that timing. A carrier reconnect can interrupt a request, but a single timeout is not evidence that the modem needs replacement.
Reproduce three failures locally
The downloadable lab creates controlled responses on 127.0.0.1. It lets you compare a rejected CONNECT request, a proxy bypass and a delayed response body without a paid account. It never forwards traffic or changes system proxy settings.
On 13 November 2026, all eight checks passed with curl 8.7.1, Python 3.9.6 and Requests 2.32.5 on macOS. The results illustrate client behavior; they do not measure mobile-network latency or rental uptime. The two Requests checks skip when that optional package is absent.
python3 proxy-diagnostics-lab.py --output proxy-lab-results.jsonSend a report support can act on
Record the exact error, time with timezone, client version, protocol, destination hostname and whether a neutral request works. Include a rental identifier through the authenticated support channel. Remove passwords, tokens, authorization headers and private page content from logs.
The downloadable template keeps those observations together. It does not run a network test or collect credentials. Fill in what you observed and leave unknown fields blank.
Download the support report template