Running AC68R behind pfsense

[SavageWS6]

Hello, I'm gonna setup a pfsense build, and got a quick question regarding my setup with AC68R

This is the network map I will have setup

Modem > pfsense > AC68R (Acting as Switch/AP)

What settings do I need to switch in the Merlin firmware in order for the router to work as a normal Switch/AP device? Under Administration, would I set it to Access Point Mode?

Would me WAN port still be usable aka assigning WAN port to the switch like you can in DD-WRT, or am I restricted to the 4 switch ports on the router, and using 1 to receive Internet Access from the pfsense build?

Sorry for the confusion ahead of time if I wasn't clear enough.

EDIT: I've done this before using DD-WRT Firmware before on a older router, but wanna make sure I can use this current network model with the AC-68R

 

[rototiller]

As far as Merlin's firmware goes I can not attest to as I do not own an ASUS router but from what I understand which I may be wrong, is that Merlin's firmware is a better version of ASUS's stock firmware, so it should be similar to ASUS's stock firmware. Your AC-68 would be used as an AP to add WI-FI to your network since your pfsense build would be your main router. Your pfsense build would be getting the WAN link and you would connect your pfsense build to a LAN port on your AC-68. Hope that helps or I may be way off.