$re = '/Host: (.*?)<br>/u';
$str = '<span style="font-weight: bold;"> Problem started at 15:14:06 on
2022.06.16<br>
Problem name: Site is Down!<br>
Host: worldbells.com<br>
Severity: Average<br>
Operational data: 100 %<br>
Original problem ID: <br>
</span>';
preg_match_all($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