Software

This may not be possible or even desirable. You need to understand the way that these devices Radio Signals propagate and how the Aerials send/receive signals.

All WiFi Access Points have Directional Aerials which tend to work in a single plane and these Radio Signals are interrupted by solid objects like walls and floors.

So if there is any metal inside the Floors/Walls this will limit the signal that can be sent/received and that is just in a single plane. So if you where to setup any WiFi Router in the normal way one floor may have a decent signal but a floor high or lower may have little to no reception.

So under ideal situations you should have one WiFi Access Point per floor and even then depending on what the building is made of you may need more than one per floor.

Col