HTTP 511 — Network Authentication Required
5xx Server Error
What it means
The client must authenticate to get network access — a captive portal on hotel or airport Wi-Fi.
What to do about it
Open a browser and sign in to the network. Nothing to fix on the server.
Where it sits
511 belongs to the 5xx family: The server failed to fulfil an apparently valid request. The fix is on the server side.
HTTP/1.1 511 Network Authentication RequiredChecking it yourself
# see the status code and headers only
curl -sI https://example.com/path
# follow redirects and print each hop
curl -sIL -o /dev/null -w "%{http_code} %{url_effective}\n" https://example.com/path
# JavaScript
const r = await fetch(url);
console.log(r.status, r.statusText);