How to track internet traffic?

Question

Computer networks

For quite a long time, to provide Internet for a small office, I use mobile Internet from Beeline. For a month, 30 gigs was always enough. And one fine day, 3 days before the traffic update, our 30 gigs suddenly ended. We decided not to pay extra and temporarily moved to the mobile Internet from a megaphone, bought 1 gig, concluding that it would be enough for 3 days, the gig ended in 2 hours. To begin with, I installed a simple utility to control traffic and it turned out that the computer was constantly downloading something. Accordingly, it continues to download with the complete absence of actions from the outside. Tell me how to figure out in detail where the traffic goes!
PS: Antivirus did not detect any infections. A Yandex disk is installed on the computer with it constantly being exchanged for small files.

Answer 1

in the command line netstat –aon, run AND track what traffic is using

Answer 2

OS what? Which city? Why Beeline? No Yota? Alternative cable providers? In general, there are a lot of questions for which you forgot to give explanations, and as you know, a well-asked question contains half the answer.
And so, I would just open the Task Manager - Resource Monitor in Win7/8/10, the Network tab, and in it I would see which process pumps how much. Killed the Virus you had or Turned off auto-updates of the OS, and continued to enjoy life / meditate.
Alternative options in the form of solutions like T-Meter, or a switch + some kind of PRTG Traffic Grapher - IMHO, the solution is too "heavy" for you.