HTTP 499 Client Closed Request vs 511 Network Authentication Required
HTTP 499 (Client Closed Request) is a 4xx Client Error response, while 511 (Network Authentication Required) is a 5xx Server Error response. 499 indicates that a non-standard status code used by Nginx when the client closes the connection before the server responds. In contrast, 511 means that the client needs to authenticate to gain network access. Used by captive portals (hotel/airport WiFi).
Description
A non-standard status code used by Nginx when the client closes the connection before the server responds.
When You See It
In Nginx logs when clients timeout or navigate away before receiving the response.
How to Fix
Optimize server response times. Check for slow upstream services.
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
499 is a 4xx Client Error response, while 511 is a 5xx Server Error response.
HTTP 499: A non-standard status code used by Nginx when the client closes the connection before the server responds.
HTTP 511: The client needs to authenticate to gain network access. Used by captive portals (hotel/airport WiFi).
You encounter 499 when in Nginx logs when clients timeout or navigate away before receiving the response.
You encounter 511 when when connecting to WiFi that requires login (airport, hotel, coffee shop).
When to Use Which
For 499 (Client Closed Request): Optimize server response times. Check for slow upstream services. For 511 (Network Authentication Required): Open a browser and complete the captive portal login process.