--- pfsense-utils.inc   2020-05-13 14:50:35.000000000 +0100
+++ pfsense-utils.inc     2020-08-15 16:18:47.828229000 +0100
@@ -569,8 +569,10 @@
 
        if (isset($config['system']['disablesegmentationoffloading'])) {
                $flags_off |= IFCAP_TSO;
+               $flags_off |= IFCAP_VLAN_HWTSO;
        } else if (isset($options['caps']['tso']) || isset($options['caps']['tso4']) || isset($options['caps']['tso6'])) {
                $flags_on |= IFCAP_TSO;
+               $flags_on |= IFCAP_VLAN_HWTSO;
        }
 
        if (isset($config['system']['disablelargereceiveoffloading'])) {