NETGEAR Nighthawk X6 AC3200 purchased to use to extend wifi range

We have a problem that our wifi connectivity seems to be limited in range and we need a little more to reach an important area.  I presently have a traditional wifi router that is necessarily located very close to my desktop cpu, printer and associated wiring.  It is located in a cabinet with no alternative locations available close by.  Some with more knowledge have suggested this location and possible interference is limiting our range.  They said that a second wireless router can be added and connected via a cat 6 that would expand our range without the reduction in strength of a normal extender.   I can mount the second router in an attic if height is helpful or even mount it's antenna external to the home's attic if that would be helpful.

I purchased a NETGEAR Nighthawk X6 AC3200 to use as the secondary router but need help in setting it up as a slave or whatever term is appropriate.  Where could I find detailed instructions on setting this unit as a secondary or additional router?

Thanks