Diagnostic Environment (Windows booted into "Safe Mode with Networking", connected to router via network cable; WiFi turned OFF in router; all other devices disconnected from router; VPN/remote links disconnected from router)

Note: to boot Windows 8/10 into Safe Mode click here

Network monitoring - can be run immediately, without entering "Safe mode"

You can view the historical logs for network usage in a few simple step:

Click the Windows logo (start) > Settings

Select NETWORK & INTERNET > Data Usage

Click Usage details to view historical usage for individual applications

Monitor the network traffic live

Monitoring the network live can be done using Task Manager (Ctrl + Shift + esc).

Click the Perfromance tab...

...now click the link Open Resource Monitor to get a detailed view of which applications are consuming bandwidth