Drobo 800fs DR Setting

This is actually for the Drobo 800fs
I have two Drobo 800fs units which are stacked one on top of another. I was wondering if there was a way to make one replicate to the other via the second RJ45 ports with a cable directly connecting them and thereby bypassing my switch when replicating. I’m trying to avoid them replicating over my main network and slowing down the other clients. Anyone know if this can be done? Thx!