I’m updating an old android app that posts a URL to a teams channel. The MessageCard contains a button with a url, however when clicked nothing happens.
I can curl the url on my laptop without any issues, the resource is on our local network.

Here is the payload I’m sending to the connector:

{
   "@context":"https://schema.org/extensions",
   "@type":"MessageCard",
   "themeColor":"F8BA00",
   "title":"Ring! Someone is at the door",
   "text":"Click **Open Door** to open the door",
   "potentialAction":[
      {
         "@type":"HttpPOST",
         "name":"Open Door",
         "targets":[
            {
               "uri":"http://172.16.2.48:9999/?open"
            }
         ]
      }
   ]
}

What might the issue be?
I’ve no problem connecting to the server myself, the server can talk to teams and generate MessageCards as it should, but for some reason the button doesn’t work.