Wrong DHCP configuration option when activating "Deny unknown clients"
There is a bug in the generated dhcpd.conf when enabling "Deny unknown clients".
the resulting option is "deny unknown clients;" but it should be "deny unknown-clients;".
To correct this bug, you need to change in
$dhcpdconf .= " deny unknown clients;\n";
$dhcpdconf .= " deny unknown-clients;\n";
Alert the user that the firewall must be rebooted after VLAN changes