R8000 WiFi sign extender

[Rays68]

Hi, I have a R8000P — Nighthawk X6S AC4000 installed, but my Signal in the garden is weak. What would you recommend me? Extender (which would you recommend AX8 for wifi6) or complete orbi mesh setup? Also upstairs, second Floor the Signal is weak (concrete Floors).

Thanks for your reply and help

[Rays68]

Oh, forgot... on the 1st Floor a ex7300v2 is installed as extender.