1. Overview of the problem
We are experiencing a persistent communication failure when our automated vendor within Second Life (through a POST request with LLHttpRequest) tries to communicate with our backend server located at https://factorycasas.es/Radio/Crear_Emisora.php.
Every transaction attempt from Second Life consistently results in an HTTP Status Code 499 (Customer closed the request/Timeout) on the LSL side, while conventional web browsers, API testing tools (such as Postman) and external HTTP clients can successfully access the endpoint, obtaining a 200 OK status in less than 50 milliseconds.
  1. Technical environment and architecture
SSL/TLS configuration: Valid certificate (Certbot/Let's Encrypt) with the complete intermediate chain configured correctly.
Backend optimization: The PHP script implements asynchronous execution in the background (fastcgi_finish_request (), ignore_user_abort () and CLI workers) to ensure that the HTTP 200 response is sent to the client instantly, eliminating any internal processing bottleneck.
  1. Symptoms and Diagnostic Findings
LSL behavior: When executing LLHttpRequest from a scripted object in the world, the request was blocked for approximately 25 seconds and was abruptly interrupted with HTTP 499, returning an empty response body (body: “”).
Network Interception Test:
When testing the endpoint using external web clients or curl from external networks, the response is immediate (HTTP/ 1.1 200 OK).
When monitoring network traffic using tcpdump on the VPS pointing to Linden Lab's known outbound IP ranges (64.129.x.x, 216.82.x.x, 162.243.x.x), incoming TLS handshakes or packets coming from Second Life regions are not recorded or appear to be completely discarded, strongly suggesting that outbound traffic from the SL simulator is being filtered, blocked or limited before reaching the server's public interface, or that the domain Destination /IP has been unintentionally marked or restricted in the simulator's outbound firewall.
Alternative access: Other domains hosted outside this VPS or specific network perimeter successfully receive callbacks (LLHttpRequest) from the exact same region without throwing error 499.
  1. Request for assistance
Since external HTTP access to factorycasas.es operates normally for all global traffic, with the exception of requests from Second Life simulator nodes, we kindly request your collaboration to:
Check if the domain factorycasas.es or the associated IP address of the VPS is currently restricted, rate-limited, or blacklisted within Linden Lab's outgoing proxy/firewall infrastructure.
Review possible output routing problems or incompatibilities in SSL/TLS ciphers between the simulator's HTTP client library and our server configuration.
Thank you in advance for your time and technical support.
I am at your disposal for any clarification.
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