Nighthawk X4 Router

[SD07]

I have a Nighthawk X4 Router. I recently finished a space above my garage and am getting spotty coverage. Is the AC750 mesh extender compatible with my router to extend coverageto this area.

[plemans]

Which model router? 

AC750 is a speed, which extender are you looking at? 

And its hard for us to say 100% if it'll work as many things impact wireless extenders including home structure, wireless interference, and distance. 

What speeds are you expecting from the extender?