Ip public through private network problem

Hello to all,

I would like to know how to solve a problem that is represented in the graphic attached to this post.
I have a bridged wireless network and the last RB is a 450G which has 4 ethernet port bridged working with a IP public,
what I am trying to do is basically split the bridge into a WAN port with a private ip and a bridge LAN (3 ether port) with the public ip network of /26

is that possible?

thanks for your help
Network.JPG

sure, just route those addresses to that router