Model : Archer C7

Hardware Version : Not Clear

Firmware Version :

ISP :

Hi,
I have 2 routers,
Main router - Archer C7
Second router - WDR4300 (Connect with wire to main router and site on my roof)

The second router is with the same SSID like the Main router, I does it instead of change SSID in my house,
WDR4300 sit on the roof, and it's have obstacle ceiling, the comprehension of wifi is nice, but not the best,
I want to know if this antenna Alfa APA-M25 will improve my WIFI ?

Regards.