A drill bit for wood... for drilling through walls? Wat?
Weren't mesh wireless networks made to help this issue?
Also 802.11aX is out soon, it will use 2.4/5ghz just with a bit more bandwidth on both, so you may want to just wait for that instead. (edit: looks to be maybe +25% or so more)
Sadly there are other things (proprietary or Bluetooth wireless accessories, for example) that only operate on 2.4GHz.