The message logged on the client’s server (shown below) isn’t related to the problem. The timeout occurs because the IP address Lambda uses needed to be whitelisted.
When running an HTTPS POST from a serverless invoke the following message is logged on the receiving server.
- Microsoft.AspNetCore.Server.Kestrel|INFO|Connection id “0HLK7NKDKAQKC”, Request id “0HLK7NKDKAQKC:00000001”: the request timed out because it was not sent by the client at a minimum of 240 bytes/second.