HTTP 203 Non-Authoritative Information vs 511 Network Authentication Required
HTTP 203 (Non-Authoritative Information) is a 2xx Success response, while 511 (Network Authentication Required) is a 5xx Server Error response. 203 indicates that the response payload has been modified by a transforming proxy from the origin server's 200 response. In contrast, 511 means that the client needs to authenticate to gain network access. Used by captive portals (hotel/airport WiFi).
Description
The response payload has been modified by a transforming proxy from the origin server's 200 response.
When You See It
When a proxy or CDN modifies the response body (e.g., adds headers, transforms content).
How to Fix
Check if a proxy is modifying the response. Access the origin directly if you need the original content.
Description
The client needs to authenticate to gain network access. Used by captive portals (hotel/airport WiFi).
When You See It
When connecting to WiFi that requires login (airport, hotel, coffee shop).
How to Fix
Open a browser and complete the captive portal login process.
Key Differences
203 is a 2xx Success response, while 511 is a 5xx Server Error response.
HTTP 203: The response payload has been modified by a transforming proxy from the origin server's 200 response.
HTTP 511: The client needs to authenticate to gain network access. Used by captive portals (hotel/airport WiFi).
You encounter 203 when when a proxy or CDN modifies the response body (e.g., adds headers, transforms content).
You encounter 511 when when connecting to WiFi that requires login (airport, hotel, coffee shop).
When to Use Which
For 203 (Non-Authoritative Information): Check if a proxy is modifying the response. Access the origin directly if you need the original content. For 511 (Network Authentication Required): Open a browser and complete the captive portal login process.