I have just found a tiny, but really nasty bug in /lib/data_query.php, line 1119.
There is a space in the pattern (at '}) {2') that breaks the recognition of octet strings like e.g. '5.103.101.48.47.49'
if (preg_match('/^\d{1,3}(\.\d{1,3}) {2,}$/', $parse_value)) {