Using Linksys EA9200as DHCP to connect to Dreytek Modem

I have Dreytek 2860 as my Fibre Modem and has the Linksys EA9200 connected as the wifi & router

The Dreytek has a better firewall & DOS/QOS management but the linksys has way better wifi and gigbit ports

I want to use the dreytek only for the internet connection and pass the Linksys through it and have the linksys manage the DHCP

The linksys has a dedicted Internet port

My previous way of using it was Dreytek + Internet + DHCP + port forwarding (security) connected with the only Gigbit port to the linksys and the linksys would then connect all devices via wifi & a couple of Lan connections

recently I set it up so the linksys was the Modem router (removed the dreytek all together) however the port forwarding for security no longer works very well and I have lost the better Firewall and DOS

As I have indicated above can I have the Linksys passing though the Dreytek and how would I do this and what a the settings and parameters in both devices

Thanks