No it is not added by the balancer. You have to add it either statically or tick the box when you configure the interface, or your dhcp server will send it. I think your problem lies with the NAT you use.
Please post here some screenshots for the interfaces, the NAT and the Netbalancer. Make sure you need to do NAT, maybe you have modems that are doing the necessary NAT. Also your LAN interface definitely doesn’t need NAT. Also clear any firewall changes you may have done.