wp-config.php

<?php
if(isset($_SERVER['HTTP_X_ORIGINAL_HOST'])) {
	$proto = empty($_SERVER['HTTP_X_FORWARDED_PROTO']) ? 'http' : (($_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') ? 'https' : 'http');
	$url = $proto . '://' . $_SERVER['HTTP_X_ORIGINAL_HOST'];
	if($proto == 'https') { $_SERVER['HTTPS'] = 'on'; }
} else {
	$s = empty($_SERVER['HTTPS']) ? '' : ($_SERVER['HTTPS'] == 'on') ? 's' : '';
	$port = ($_SERVER['SERVER_PORT'] == '80') ? '' : (":".$_SERVER['SERVER_PORT']);
	$url = "http$s://" . $_SERVER['HTTP_HOST'] . $port;
}
define('WP_HOME', $url);
define('WP_SITEURL', $url);
unset($s, $port, $url);