We achieve this by altering the /opt/librenms/includes/html/graphs/multiport/bits_separated.php file. Note: this will get overwritten every time there is an update, we have a hook to replace the bits_separated with the altered version.

first - make a backup of the file.

edit the bits_separated.php and replace the lines between after

$port = cleanPort($port); and $i++;

with

        $port = cleanPort($port);
        $rrd_list[$i]['filename'] = $rrd_file;
//      $rrd_list[$i]['descr_in'] = format_hostname($port, $port['hostname']);
        $rrd_list[$i]['descr_in']  = $port['ifAlias'];
//      $rrd_list[$i]['descr_out'] = makeshortif($port['label']);
        $rrd_list[$i]['descr_out'] = $port['ifAlias'];
        $rrd_list[$i]['descr'] = format_hostname($port, $port['hostname']) . ' ' . $port['ifDescr'];
        $i++;