5xx Server Error
511 Network Authentication Required
The client must authenticate to gain network access — a captive portal.
What causes it
- Hotel, airport or café Wi-Fi intercepting traffic before you sign in.
How to fix it
- Open any plain HTTP page to trigger the portal. This status exists so intercepting proxies stop faking 200s.
At a glance
- Class
- 5xx Server Error
- Reference
- RFC 6585 §6
- Standardised
- Yes
- Retry the request?
- Only if idempotent
Other 5xx server error codes
- 500 Internal Server Error
- 501 Not Implemented
- 502 Bad Gateway
- 503 Service Unavailable
- 504 Gateway Timeout
- 505 HTTP Version Not Supported
- 506 Variant Also Negotiates
- 507 Insufficient Storage
- 508 Loop Detected
- 510 Not Extended
- 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