I found a solution. If I let the nanostation receive an ip via dhcp from the RB433 rather than assign a static ip, I am then able to access the interface. I wonder why it makes a difference?
I wanted to revisit this because I am still want to figure out why I can not reach the nanostation unless I let the routerboard assign it an ip address via dhcp. If I assign the nanostation a static ip in the same subnet it is not reachable.
I've tested this on multiple segments of my network with different pieces of equipment and it still does not work.