HTTP 511 Network Authentication Required indicates the client needs to authenticate to gain network access. This is used by captive portals — the Wi-Fi login pages you see at hotels, airports, and coffee shops that intercept HTTP requests until you log in.
Status
511 Network Authentication RequiredExample
GET / HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0
Accept: text/htmlHTTP/1.1 511 Network Authentication Required
Content-Type: text/html; charset=utf-8
Location: http://wifi.example.net/login
Content-Length: 271
<!doctype html>
<html lang="en">
<head>
<title>Network Login Required</title>
</head>
<body>
<h1>Network Login Required</h1>
<p>You must sign in to use this network.</p>
<p><a href="http://wifi.example.net/login">Click here to log in</a></p>
</body>
</html>How to Troubleshoot
Open a browser and navigate to any HTTP page
The captive portal should intercept the request and redirect you to the login page. Try navigating to http://example.com (not HTTPS).
Look for the captive portal login
Most operating systems detect captive portals automatically and show a login prompt.
Try a different network
If the captive portal is broken, switch to mobile data or a different Wi-Fi network.
Common Causes
Captive portal authentication
highThe network requires you to log in through a captive portal before allowing internet access (common on public Wi-Fi).
Related Status Codes
References
| Specification | Section |
|---|---|
| Additional HTTP Status Codes | RFC 6585 §6 |
Frequently Asked Questions
This reference was compiled from official RFCs, protocol specifications, and hands-on troubleshooting experience. AI tools were used primarily for formatting and organizing the content on the page.