511 Network Authentication Required — Causes & Fix
HTTP 511 (Network Authentication Required) means the client needs to authenticate to gain network access — typically a captive portal (public Wi-Fi login page).
- Applies to
- Any website or web server (HTTP standard)
- Time to fix
- 15 minutes – 2 hours
What it means
Returned by captive portals (hotels, airports, cafés) that require you to log in or accept terms before using the internet. This is a server-side (5xx) error defined in RFC 9110 (HTTP Semantics) — the request was valid, so the fix is on the server/origin side, not the visitor's.
Symptoms
- "511 Network Authentication Required"
- Redirected to a Wi-Fi login/terms page
How to fix it
- 1
Complete the network login
1. As a user: open a browser, load any page, and finish the captive-portal login/terms.
- 2
Configure the portal (operator)
1. Ensure the captive portal returns 511 and redirects users to the login page correctly.
Frequently asked questions
Why do I see 511 on public Wi-Fi?
The network wants you to log in or accept terms first (a captive portal). Complete that login and normal browsing resumes.
Last updated July 20, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.