What is the main issue the user is facing with PHP while trying to retrieve XML content from another page?

The main issue the user is facing is likely related to retrieving XML content from another page using PHP. To solve this issue, the user can use PHP's built-in function `file_get_contents()` to fetch the XML content from the URL and then parse it using `simplexml_load_string()` to work with the XML data.

$url = 'https://example.com/data.xml';
$xml_content = file_get_contents($url);
$xml = simplexml_load_string($xml_content);

// Now you can work with the XML data stored in the $xml variable