Starting with Windows 10 system updates can be distributed via peer to peer, in much the same way as a BitTorrent.
All versions of Windows 10 apart from Enterprise and Education have peer to peer sharing of Windows updates to the Internet enabled by default.
If you don't alter this setting it could consume some of your bandwidth allowance on a wired connection.
Here's how to change the settings to disable this:
Go to Start , then Settings > Update & security > Windows Update , and then select Advanced options.
On the Advanced options page, select Choose how updates are delivered, and then use the toggle to turn Delivery Optimization off. When turned off, you'll still get updates and apps from Windows Update and from the Windows Store.
If you'd just like to stop downloading updates and apps from PCs on the Internet, select PCs on my local network. (this option is also OK as local network traffic is free, and this setting may actually save you some bandwidth!).