If you're using a portable hotspot (e.g. mobile tethering or MiFi device), be sure to set Windows 10 to treat it as a metered connection. Otherwise a 4G LTE connection will look like a high speed broadband connection to WIndows, which it will potentially use to distribute Windows updates. This may also explain some threads I'm seeing in mobile operator forums about unexpected excessive usage charges when the user claims to only use the connection for e-mail and limited Internet access.
To configure your portable hotspot as a metered connection, first connect to it and perform the following steps:
1. Go into the Start menu and into Settings.
2. Go into "Network & Internet"
3. Ensure your hotspot shows "Connected" (if not, connect it)
4. Click 'Advanced Options'
5. Turn on "Set as metered connection".
In Windows 8.1, this was quite an easy task - Just click the Wi-Fi icon in the task tray and click "Set as metered connection" in the menu that appeared. This should also stop Windows using it for Windows updates, which have been getting rather large recently. I remember when Windows 7 Service Pack 1 seemed massive update at over 900MB and now it seems normal to get over 1GB worth of regular Windows updates on patch Tuesday. Not something you want eating into the tiny monthly data allowances most mobile providers offer, let alone Windows then distributing these updates over it!