Why Do Proxies Fail? Troubleshooting Common Errors
1. HTTP 407 (Proxy Authentication Required)
This status indicates the proxy server received your connection request but rejected the credentials. Check if your username or password contains special characters that require URL-encoding, or verify whether your client IP must be whitelisted on your provider's dashboard.
2. Connection Timed Out (ETIMEDOUT)
A timeout occurs when the proxy host or port is completely unreachable. Common causes include firewall blocks on the destination port, server downtime, or mobile carrier proxy IP rotation while a session is mid-flight.
3. SOCKS5 vs HTTP Protocol Mismatches
Connecting to a SOCKS5 proxy port using an HTTP client (or vice versa) results in dropped packets or invalid header errors. Always verify whether your proxy endpoint uses HTTP/HTTPS or SOCKS5.
4. Local vs Remote DNS Leaks (SOCKS5 vs SOCKS5h)
When testing with cURL, using socks5:// resolves DNS requests locally on your home network, leaking your real ISP identity. Always specify socks5h:// to ensure domain name resolution executes remotely on the proxy exit node.