Well, somebody sure slipped a cog on that one !
The data has to be going ... somewhere ......
The usual procedure is to take a screenshot of your status meter and note the time just before shutting down your computer .... and disconnecting the LAN cable from the rear of the modem .... as you did long ago.
Then reconnect the LAN cable just prior to startup and again noting the time.
Post the two screenshots along with the two times here in the Community and ... we will bump your post relentlessly so it doesn't get lost again.
There are so many variables if a user has a router in terms of potential "leaks" that we ask that the user remove the router during trouble shooting and connect single computer directly to the modem.
Many of us also run the free version of a program called GlassWire that really helps track usage by program or process.
Glasswire can be found here:
As an example I installed the latest version of Win10 Preview (3.85 GB download) and after installation Glasswire showed that nearly 450 MB was downloaded while I was still in the process of getting things as much under control as one can with Win10:
(Click on pic for larger image)
Remember, Glasswire will only track and display the usage of the single device upon which it is installed.