5xx

511 Network Authentication Required

The client needs to authenticate to gain network access, typically via a captive portal.

What is HTTP 511?

This status code indicates that the client needs to authenticate to gain access to the network. It is typically generated by intercepting proxies such as captive portals at hotels, airports, or coffee shops that require users to accept terms or log in before granting internet access. The response should contain a link to the authentication page where the user can provide credentials or agree to terms.

Defined in RFC 6585

Common Causes

  • A Wi-Fi captive portal at a hotel, airport, or cafe requiring login before internet access
  • A corporate network requiring authentication through a web portal
  • A public network requiring acceptance of terms of service before granting access

How to Fix

  • Open a browser and navigate to any HTTP page to trigger the captive portal login page
  • Complete the authentication or accept the terms on the captive portal page
  • If the portal does not appear, try visiting a non-HTTPS URL like http://neverssl.com
  • Contact the network administrator if you cannot access the captive portal