11205: HTTP connection failure

There was a network failure attempting to connect to this URL. Twilio will try for 10 seconds to establish a TCP connection to your URL (two 5-second attempts). Twilio will wait for a total of 15 seconds to receive an HTTP response. This includes the TCP connection time, so if it took six seconds to establish a TCP connection, your server would have 9 seconds to deliver an HTTP response. If either of those timers expire, we fail the request, fire a notification, and try your fallback URL, if one is specified.

• Network outages between Twilio and your web server.
• URLs that reference private IP addresses or localhost.
• Twilio's TCP timeout is 10 seconds. If you see an error in Request Inspector after more than 10000 milliseconds, Twilio could locate your server, but could not establish a TCP connection with it.
• Twilio's HTTP timeout is 15 seconds. If you see an error in Request Inspector returned after more than 15000 milliseconds, Twilio was able to establish a TCP connection with your server, but the HTTP response from the server failed.

• Verify the URL provided is accessible to the public internet.
• Verify network connectivity to your web server.
• Check your TCP logs to verify inbound connection attempts are successful.
• Check HTTP server logs to verify a response was generated and returned within the timeout.
• Check your edge element logs to verify responses are making it out of your infrastructure.