HTTP 511 Network Authentication Required

What HTTP 511 means

Hotel, airport and café Wi-Fi intercept requests until you accept their terms. 511 lets them signal that clearly instead of returning a fake page that looks like the site you asked for.

Retrying

Rarely. The server can’t handle this request, so retrying it unchanged is unlikely to help.

Example response

HTTP/1.1 511 Network Authentication Required
Date: Wed, 21 Oct 2026 10:30:00 GMT
Content-Type: application/json

How to return 511

res.status(511).json({ error: 'Network Authentication Required' });

from fastapi import HTTPException

raise HTTPException(status_code=511, detail="Network Authentication Required")

http.Error(w, http.StatusText(http.StatusNetworkAuthenticationRequired), http.StatusNetworkAuthenticationRequired)

location /private/ {
    return 511;
}

Related status codes

• 407 Proxy Authentication Required : The client must authenticate with a proxy before the request can go through.
• 401 Unauthorized : The request needs valid authentication credentials.

Other 5xx status codes

500 Internal Server Error · 501 Not Implemented · 502 Bad Gateway · 503 Service Unavailable · 504 Gateway Timeout · 505 HTTP Version Not Supported · 507 Insufficient Storage · 508 Loop Detected · 520 Web Server Returned an Unknown Error · 521 Web Server Is Down · 522 Connection Timed Out · 523 Origin Is Unreachable · 524 A Timeout Occurred · 525 SSL Handshake Failed · 526 Invalid SSL Certificate

See the full list of HTTP status codes.

Sources

• RFC 6585
• IANA HTTP Status Code Registry
• MDN: 511 Network Authentication Required

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Frequently asked questions