511 Network Authentication Required

What it means

Used by captive portals on hotel, airport, or café Wi-Fi to prompt sign-in.

Common causes

• Connecting through a captive portal Wi-Fi network.

How to fix it

1. Open a browser and complete the Wi-Fi sign-in page.

Example response

HTTP/1.1 511 Network Authentication Required
Content-Type: text/plain; charset=utf-8

Worked example

A laptop joins a hotel Wi-Fi network and a request receives 511 before reaching the destination website. The user completes the network's captive-portal sign-in, then retries the original request. This is a network access prompt, not an origin site's login response; check the Wi-Fi connection before changing application credentials.

How to read this response

1. Find the status line in your browser's Network panel, API client, or server access log.
2. Read the response body and headers shown above; headers such as Location, Allow, Retry-After, and WWW-Authenticate explain the next step.
3. Use the code's class to orient your diagnosis: informational, successful, redirected, request-related, or server-side.

How to check a status code

Enter a URL in the HTTP Status Checker to see its status code, every redirect hop, and response time. For redirect-heavy pages, the Website Speed Test shows how much time redirects add.

Frequently asked questions

What it means: HTTP 511

511 Network Authentication Required: The client must authenticate to gain network access.

Common causes: 511

Connecting through a captive portal Wi-Fi network.

How to fix it: HTTP 511

Open a browser and complete the Wi-Fi sign-in page.

Tools