HTTP 511 Network Authentication Required

What does HTTP 511 mean?

The client must authenticate to gain network access. Used by captive portals in hotels, airports and cafés to signal that you need to log in to the Wi-Fi before browsing.

5xx Server error: The request looked valid, but the server failed to fulfil it. The fix is on the server side.

How to fix 511 Network Authentication Required

• Open any page and complete the network login.

511 and SEO

No SEO impact — it is generated by the network, not your site.

Example response

HTTP/1.1 511 Network Authentication Required

How to return a 511 response

Node.js (Express)

res.status(511).json({ error: 'Network Authentication Required' });

PHP

http_response_code(511);

Python (Flask)

return {'error': 'Network Authentication Required'}, 511

Go (net/http)

w.WriteHeader(511)

nginx

return 511;

Related status codes

• 401 Unauthorized — Authentication is required and has failed or not been provided.

Check which status code a URL returns with the HTTP header checker.