Please explain to me like if im 7, I’m really not good at this

Our wifi and Ethernet is installed on 2nd floor And when I’m in the basement the wifi barely works and keeps disconnecting often, unless if i stay on a specific place of the basement and rven though the internet speed is like 50% slower in there

I’m looking for the best way share the internet to the basement without losing a significant amount of internet speed

Preferably without using cables to to connect from 2nd floor to the basement because that will be troublesome

Thank you very much