If You're close to the edge with a wifi, it's difficult for a FileMaker connection. One needs constant network speed (+/-)
- repeater migth encrease the signal but decreases speed
- powerline boxes are dependant on the quality of the wire (and won't go easily 'through different accounting boxes')
- a weak wifi will have less speed than a medium-range 4G network
I prefere an ethernet-connection from floor to floor, if possible
I've used TP-Link WiFi repeaters several times in the past with success. They offer a couple different flavors, so pick one that seems to fit your environment the best. Good luck!
I installed a netgear repeater, signal/connecting was good, but the speed was not that good
I tested the placing of the wifi router - a change of some meters made a big difference. You can also have two wifi routers bridged (I did this with Apple's airport stations, together with the 'best place' the best solution - besides of an ethernet/fibre connection from floor to floor
Use a high quality wifi router as your first point. You did not write anything about your present setup, but this is the first step.
Then set up another high quality wifi router, preferably connected through ethernet. If that's not possible then via wifi.
And Markus is of course right: If it is for work, work, work you should even consider ethernet all the way.
Just adding: If in doubt, have your wifi network measured by a local network specialist and let the specialist help you setting it up.
By ethernet/fiber connection from floor to floor, I was thinking about two wifi routers, both connected via cable to a switch. Best is a 'real wired' connection over ethernet - but not very popular today...
We have problems here with conventional cabeling (no space left...) - but a fibre cable is ok...