Using readyNAS 4220 on multiple subnets

I am having a problem configuring my ReadyNAS 4220. I am using eth0 on a public lan port with a 255.255.240.0 netmask and defined gw. Then I am trying to bond 3 adapters to go to a private network with a netmask of 255.255.255.0 and no GW but it will not let me leave it blank, so I set it to an arbitrary address as there is no router on that segment. I am using LACP on the bond and the switch. As soon as I make the bond I lose the ability to ping the public network IP and I cannot ping the private ip on the private network. As soon as I set the bond to dhcp which there is no dhcp server on that segment, then I can ping the public again. It acts like the router is a global setting for all nics and same with the netmask. I really need to add a third segment to this also, but so far not having any luck getting two segments to work.