Android Internet not connecting

I have a simple method that is attempting to connect to the internet. It works in the Unity editor and in a standalone build, however it doesn't on Android.

 public static IEnumerator Login(string username, string password, Action complete)
 {
     WWW reader;
 
     do
     {
         string url = string.Format(UrlStart + "Login.php?user={0}&pass={1}", username, password);
         reader = new WWW(url);
         yield return reader;
     }
     while (reader.error != null);
 
     Logger.Log(LogTopic.Framework, "Logged in as " + username);
     complete();
 }

As you can see there's not a lot to it, yet for some reason it doesn't work. I made sure internet is a requirement in the player settings, my phone's internet is turned on. I even manually typed in the URL on my phone (in the browser), and I got the results I expected.

What would cause this?