it depends on where you are placing the HB410 within the level. WIFI signals will degrade when passing through concrete walls so if your HB410 is placed in a corner on the level, you will likely have very poor or no signal on the opposite corner on the same level. eg, if you place the device on the south-west corner, the room in the north-east corner on the other end may not have good signal coverage.
placing the device in the middle of the level technically can provide better coverage but again signal quality will degrade when passing through walls.
APs on the ceiling will also have similar issues but since they are casting the signal downwards radially, it might be better than a AP located at 1m above the floor.
So for your case if you don't want AP in the ceiling, then you may need more HB410 or similar devices on each level. I would suggest don't bother with trying to do mesh as mesh network will work best when there's line of sight between the devices. If there's multiple walls between the devices, the mesh will not work well. Just plug the devices into LAN points and use wired backhaul for best performance.
With this said, plan for at least 2 LAN points in each room so you can play around with the placements of the WIFI devices for optimal performance. Remember to provision for 13A socket(s) next to the LAN points as well so you can power up the devices.
