511Network Authentication Required

The network you are on wants you to log in before it will let any traffic through.

When you see it

Captive portals: hotel, airport and cafe networks that intercept your traffic until you accept terms or sign in. The site you asked for never saw the request.

It exists so software can recognise a captive portal instead of concluding the internet is broken. Many portals still redirect instead of sending 511, which is why devices sometimes fail to show the login page automatically.

Often confused with

407 Proxy Authentication Required

Both are intercepted before reaching the destination. 407 is a configured proxy asking for credentials; 511 is a network you have joined demanding you sign in to it first.

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Status codes

69 of 69 codes. Click a row to copy it.

1xx Informational (4)

2xx Success (10)

3xx Redirection (8)

4xx Client errors (31)

5xx Server errors (16)