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.
The network requires you to log in through a captive portal before allowing internet access (common on public Wi-Fi).
The captive portal should intercept the request and redirect you to the login page. Try navigating to http://example.com (not HTTPS).
Most operating systems detect captive portals automatically and show a login prompt.
If the captive portal is broken, switch to mobile data or a different Wi-Fi network.