<?

$str="(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=FQDN1)(PORT=1234))(ADDRESS=(PROTOCOL=TCP)(HOST=FQDN2)(PORT=5678))(ADDRESS=(PROTOCOL=TCP)(HOST=FQDN3)(PORT=9012))(ADDRESS=(PROTOCOL=TCP)(HOST=FQDN4)(PORT=3456)))(CONNECT_DATA=(SERVICE_NAME=STUFF)))";
preg_match_all('/\(HOST=(FQDN\d)\)\(PORT=(\d+)\)/', $str, $matches, PREG_SET_ORDER);
foreach($matches as $k=>$match)
    array_shift($matches[$k]);
    
var_dump($matches);
?>