Making RT-AC87U my primary wireless source on Uverse

Team,

Im a noob here but somewhat smart on electronics.
And I need your help...

I have ATT Uverse gigabit ethernet with their stock (crap) wireless modem/router.

I bought the RT-AC87U & love that it has strong signal strength.
Now comes the moment of truth of setting up the RT unit to be my wireless source for all TVs, Cellphones, etc, in my home & to turn off the other.

But how do I do that?
Is it as simple as putting the RT into bridge mode & then hard wiring it to my ATT unit (while...

Making RT-AC87U my primary wireless source on Uverse