$re = '/(\w+)=\"\s*(.*?)(?:\sMbps|\sdB)?\"/';
$str = 'var conn_down=" 13.35 Mbps";
var conn_up=" 0.82 Mbps";
var line_down=" 34.60 dB";
var line_up=" 19.70 dB";
var noise_down=" 6.10 dB";
var noise_up=" 6.50 dB";
var sys_uptime="74523";
var lan_status="Link up";
var lan_txpkts="1294024";
var lan_rxpkts="2256747";
var lan_collisions="0";
var lan_txbs="10004";
var lan_rxbs="35259";
var lan_systime="74523";';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php