Help with AC2300 R7000p near-dead zone

Thanks. I guess I should have added a little more information. Right now, I am a little hesitant to move the main router because it's also got ethernet connections to smart tv, apple tv, and PS4 in an attempt to improve streaming and gaming. Ideally I would have put it on the 1st floor but there was 1 existing run from 2nd floor to basement and with finished walls/basement and no direct runs between floors, i thought it was easier to push the basement devices and hope for the best with wifi elsewhere.

do you (or anyone else) have a recommendation for extender that works with the Ac2300 R7000P? Thanks!