How to enable my RT-AC5300 to work as a router behind Nokia G-140C-W?

[sijuthomas98]

My internet plan upgrade came with a new combo ont modem/router nokia G-140c-w, Inspite of setting one of the lan ports as bridge Im unable to use the Rt-Ac5300 as a router, On the G-140 settings there is Vlan enabled , user id and password and some settings as well .Any help will be much appreciated . The connection is a fiber PPoE type.
I'm on Asus Merlin latest stable release.