I would suggest loading GlassWire:
The free version is fine. GlassWire will only track data usage on the single computer that it is installed on.
If you have multiple computers it will need to be installed on each machine and the results added together.
That still leaves other connection paths unmonitored .... guest networks and other wireless connections.
I suggest hooking a single computer directly to the modem. Turn of wifi if you have the Exede wireless modem.
How To Limit Upload Traffic Bandwidth in OneDrive;