Local HTML containing SWF can't connect to the Internet

My Flash project downloads data from the Internet through a PHP page on my website. It works properly in the following environments, but it won't work when I try to test it with a local HTML file that contains the SWF.

My SWF can connect to the Internet in:

Adobe Animate Test (Ctrl+Enter)
Adobe Animate Debug (Ctrl+Shift+Enter)
Standalone Flash Player
On my website in HTML (www.myWebsite.com/myFlash.html)

My SWF CANNOT connect to the Internet in:

local HTML file containing the SWF (C:\test\myFlash.html)

Is it possible to use a local HTML with embedded SWF to connect to the Internet? I've been trying to get it to work in Chrome, MS Edge, and IE11, but I have been unsuccessful.

Here is my HTML:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Test</title>
  </head>
  <body style="background-color:#f0f5f8">
    <object width="1280" height="720" data="Main.swf" style="border:1px solid black; margin-left: auto; margin-right:auto; display:block">
      <param name="movie" value="Main.swf" />
      <param name="quality" value="high" />
      <param name="bgcolor" value="#000000" />
      <param name="play" value="true" />
      <param name="loop" value="false" />
      <param name="wmode" value="direct" />
      <param name="scale" value="showall" />
      <param name="menu" value="false" />
      <param name="devicefont" value="false" />
      <param name="salign" value="" />
      <param name="allowScriptAccess" value="always" />
      <param name="allowFullScreenInteractive" value="true" />
    </object>
  </body>
</html>

Edit: I made my SWF output the error message, and now when I try to play it in a local HTML, a TextField displays "securityError - Error #2048". That seems to be in regard to having a crossdomain.xml on the website, which I do have at www.myWebsite.com/crossdomain.xml:

<?xml version="1.0" ?>
<cross-domain-policy>
  <site-control permitted-cross-domain-policies="master-only"/>
  <allow-access-from domain="*" />
</cross-domain-policy>

Solution

I figured it out. I had to change this line in my crossdomain.xml from this:

<allow-access-from domain="*"/>

to this:

<allow-access-from domain="*" secure="false"/>

My site is actually https://www.myWebsite.com/, which means I needed secure="false" so that non-https sites could access it.