Canvas LTI works on AWS dev but returns Invalid consumer key on production (Load balancer)

I am implementing a basic canvas LTI from a client to our AWS EC2. It works fine when the endpoint is our dev EC2. However, when the endpoint is our live site, in which the EC2s are behind a load balancer, it fails with "Invalid consumer key"

The base code is exactly the same and the EC2s are all from the same AMI.

Any ideas are appreciated!

The issue is that the aws load balancer was connecting to the EC2 targets via http port 80 and this was causing oauth to fail.

I am not sure how changing/adding https/443 to the Target groups will affect my autoscaling group and health checks etc, so I edited the OAuth.php file, removing the part in the from_request function that checks if the server is https because we'll always be connecting via https for this.

Changed this:

public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {
    $scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on")
              ? 'http'
              : 'https';
    $http_url = ($http_url) ? $http_url : $scheme .
                              '://' . $_SERVER['SERVER_NAME'] .
                              ':' .
                              $_SERVER['SERVER_PORT'] .
                              $_SERVER['REQUEST_URI'];

To this:

 public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {        
        $scheme = 'https';
        $http_url = ($http_url) ? $http_url : $scheme .
            '://' . $_SERVER['SERVER_NAME'] .
            ':' .
            443 .
            $_SERVER['REQUEST_URI'];