All HTTP status codes

HTTP 511 Network Authentication Required

Server Error

The network (not the website) requires authentication first — the response captive portals send before you log in to hotel/airport Wi-Fi.

Defined in RFC 6585

Common causes

  • Captive portal intercepting traffic until network login

How to fix it

  1. Open the portal page and authenticate to the network

  2. In apps, detect 511 and prompt the user to complete the portal login

Related status codes

401 Unauthorized

Authentication is required and was missing or invalid. Despite the name, it means "unauthenticated" — the response includes a WWW-Authenticate challenge.

407 Proxy Authentication Required

Like 401, but the authentication challenge comes from a proxy between you and the target (Proxy-Authenticate header).

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