511
HTTPSERVER_ERRORNotable5xx Server ErrorHIGH confidence
Network Authentication Required
Production Risk
Low. This is the standard mechanism for captive portals to function. It is a user-level issue, not a server-level one.
What this means
The client needs to authenticate to gain network access. This status is not generated by origin servers, but by intercepting proxies that control access to the network (e.g., 'captive portals' in hotels or airports).
Why it happens
- 1A user connects to a public Wi-Fi network and tries to access a website before logging into the network's portal.
- 2The captive portal intercepts the HTTP request and returns a 511 response to redirect the user to a login page.
- 3This indicates that authentication is required with the network infrastructure, not the destination server.
How to reproduce
A user on a hotel Wi-Fi network opens their browser to go to example.com, but is shown the hotel's login page instead.
trigger — this will error
trigger — this will error
GET http://example.com/ HTTP/1.1
expected output
HTTP/1.1 511 Network Authentication Required
Fix
Authenticate with the Network
WHEN You are the user.
Authenticate with the Network
Complete the login or payment process on the captive portal page presented by the network.
Why this works
User Action
Sources
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