Main router with multiple AP setup

[empyrials]

So this is a dumb question but i just can't find the answer.

After several issues with my 3xAC68U with AiMesh, i'm moving on to Merlin firmware. I currently am running a standart DDWRT router for internet access, and i want to setup my 3 AC68U's as AP's. Do i need to setup one of them as a "Wireless router"(turning off DHCP of course) and setup the other 2 as APs? or just as simple as putting them all in the AP operation mode?

 

[ColinTaylor]

or just as simple as putting them all in the AP operation mode?

This.

 

[empyrials]

This.

Thanks! feel free to delete thread lol