setup help design (Nighthawk(R) X4S R7800 or RBK53S-100NAS)

Hi all.  need some help   I currently have a FVS318Gv2 doing my dhcp and routing.  off this firewall / router i have a 24 port switch.   In the invironment i have a Nighthawk(R) X4S R7800 in ap m...