Issues with SSL Error

On my OVMS module I can make the following request to a HTTPS test/demo Postman endpoint and it works perfect:

var req = HTTP.Request("https://postman-echo.com/get?foo1=bar1&foo2=bar2");

But when I try to do a similar request to my own API at "https://api.triggermouse.com/api/values" I get the following back:

{
  "url": "https://api.triggermouse.com/api/values",
  "done": function () { [ecmascript code] },
  "fail": function () { [ecmascript code] },
  "redirectCount": 0,
  "error": "SSL error"
}

Reading through the docs it does mention the following for HTTP requests: "you may need to install a custom root CA certificate...". So I went ahead and got the .PEM from my web server, and did the following as described here: https://docs.openvehicles.com/en/latest/userguide/ssltls.html. But no luck. Anyone have any ideas why the Postman HTTPS request works, but why my web server does not? Thanks in advance!

-Jake