Maybe you need the full absolute path instead something like
/www/dmxConnect/api/propertyDetail.php?property_slung=xxx-huatulco-5b2 and maybe take other examples from PHP: file_get_contents - Manual
Maybe you need the full absolute path instead something like
/www/dmxConnect/api/propertyDetail.php?property_slung=xxx-huatulco-5b2 and maybe take other examples from PHP: file_get_contents - Manual