511
Network Authentication Required
Server errors (5xx)·RFC 6585
What 511 means
The client must authenticate to gain network access (e.g. a captive portal).
Returned by intercepting proxies such as Wi-Fi hotspots that require a login before allowing traffic.
Server errors (5xx)
The server failed to fulfil an apparently valid request.
Other 5xx codes
FAQ — 511
What does HTTP 511 mean?
511 Network Authentication Required: The client must authenticate to gain network access (e.g. a captive portal). Returned by intercepting proxies such as Wi-Fi hotspots that require a login before allowing traffic.
Which class does status code 511 belong to?
511 is a Server errors (5xx) code. The server failed to fulfil an apparently valid request.
Where is the 511 code defined?
Status code 511 is defined in RFC 6585 and is part of the IANA HTTP Status Code Registry.