Solved [USB tethering] Windows eats up my data plan

Winfried · 2026-06-28T06:21:33-0400

Hello,

I noticed a problem that I already had on Windows10 and experience again on Windows11 to which I migrated months ago: After connecting my Android phone to Windows through USB tethering and sharing its memory (ie. file transfer mode, not just charging), Windows or some application mistakenly use that Internet connection instead of going through the fiber connection. As a result, it eats up my small 2GB data plan, and I'll have to do wtihout until the middle of next month when the reset occurs :-/

Has someone also experienced that problem? Is there a way to know if it's Windows or some specific application that takes the wrong route to the Net?

As a temporary fix, I'll have to always remember to turn off the data connection before connecting the phone through USB in file transfer mode.

Thank you.

giftwrapped · 2026-06-28T07:06:53-0400

I think there’s a small mix-up between two USB modes.

File transfer (MTP) is just for copying files/photos or charging — it doesn’t use mobile data at all and can’t give internet to your PC.

USB tethering is something different: it shares your phone’s mobile data with Windows and turns the phone into a network connection.

So if Windows is showing data usage from the phone, it pretty much means USB tethering was turned on at some point (even briefly). File transfer mode by itself can’t do that.

Winfried · 2026-06-28T08:02:25-0400

Sorry for the error. I meant that some application goes through my phone instead of fiber to rech the Net when I turn on "USB tethering" with the phone physically connected to the computer.

Helmut · 2026-06-28T08:23:45-0400

It's your Phone settings not Windows.
This is for my Samsung:
Settings > Connections > Data usage > Mobile data > OFF.

It is that which really matters, not your USB or WiFi connection mode. Mine is currently connected by WiFi and USB but zero mobile data usage.
Mobile Hotspot and Tethering is entirely greyed out(unavailable) on mine, as it should be.

giftwrapped · 2026-06-28T08:34:46-0400

You should never need to turn on USB-tethering on your Phone when transfering files/images or charging your phone. When I connect my Android phone to my PC, I see a popup window on my phone where I can choose between: File transfer, image transfer or charging.
I am connected to internet by Mobile Data only (my current data plan:108 GB/month), that's why I use USB-tethering.

Ghot · 2026-06-28T19:07:42-0400

Winfried said:
Sorry for the error. I meant that some application goes through my phone instead of fiber to rech the Net when I turn on "USB tethering" with the phone physically connected to the computer.

I too, hook phone to PC to charge AND transfer files. Starting with One UI 8.0... you need to do the following...

Samsung Begins Official Rollout of One UI 8 to Galaxy Devices

Samsung Newsroom: Samsung Electronics today announced the official rollout of One UI 8 — introducing advanced multimodal AI capabilities, a UX optimized for different device form factors and personalized, proactive suggestions to make everyday life smarter and more convenient. Starting this week...

www.elevenforum.com

Then you'll be able to hook phone to PC with USB cable and it will charge AND allow file transfers.

Winfried · 2026-06-29T01:58:26-0400

Helmut said:
It's your Phone settings not Windows.
This is for my Samsung:
Settings > Connections > Data usage > Mobile data > OFF.

It is that which really matters, not your USB or WiFi connection mode. Mine is currently connected by WiFi and USB but zero mobile data usage.
Mobile Hotspot and Tethering is entirely greyed out(unavailable) on mine, as it should be.

I didn't expect to have to turn off mobile data to prevent Windows from using that connection when I enable USB tethering, but I guess it's "normal"?

giftwrapped said:
You should never need to turn on USB-tethering on your Phone when transfering files/images or charging your phone.

It's not about file transfer or charging: One app I use requires USB tethering to sync between Windows and Android, which is why I bother with USB tethering.

Is it simply impossible to enable USB tethering to let that app do its thing while forbidding Windows from mistakenly using that connection to reach the Internet? Should I 1) disable data access and 2) enable USB tethering each time?

giftwrapped · 2026-06-29T08:08:49-0400

@Brink has written this very good tutorial, I hope it will solve the problem

Change Network Adapter Interface Connection Priority Order in Windows 11

ChatGPT suggested these values:
Primary internet (fiber / Wi-Fi), Interface metric: 10
USB-tethering (phone), Interface metric: 500

Helmut · 2026-06-29T08:12:38-0400

Winfried said:
One app I use requires USB tethering to sync between Windows and Android, which is why I bother with USB tethering.

Is it simply impossible to enable USB tethering to let that app do its thing while forbidding Windows from mistakenly using that connection to reach the Internet? Should I 1) disable data access and 2) enable USB tethering each time?

Your problem is the App requiring USB tethering which involves using Mobile Data. Find another more suitable App.

My phone says this for USB tethering - "Share your phone's internet connection using a USB cable".

Winfried · 2026-06-29T08:17:15-0400

giftwrapped said:
@Brink has written this very good tutorial, I hope it will solve the problem

Thanks very much!

Helmut said:
Your problem is the App requiring USB tethering which involves using Mobile Data. Find another more suitable App.

Can't do, but thank anyway.

SlicEnDicE · 2026-06-29T10:06:54-0400

Winfried said:
I didn't expect to have to turn off mobile data to prevent Windows from using that connection when I enable USB tethering, but I guess it's "normal"?

Don't enable tethering...you don't need that at all for charging or file transfers.

SlicEnDicE · 2026-06-29T10:08:30-0400

Winfried said:
One app I use requires USB tethering to sync between Windows and Android, which is why I bother with USB tethering.

Which app? Stop using it. Period.

EDIT: Syncthing?

gunrunnerjohn · 2026-06-29T10:45:21-0400

This really makes no sense. If the app requires mobile data, why does it still work when you disable mobile data? I don't use any special app when I connect my phone to access it's files, I just enable file sharing and use Windows Explorer.

SlicEnDicE · 2026-06-29T10:56:16-0400

gunrunnerjohn said:
This really makes no sense. If the app requires mobile data, why does it still work when you disable mobile data? I don't use any special app when I connect my phone to access it's files, I just enable file sharing and use Windows Explorer.

When you use tethering, there is created a local network (LAN similar to when you connect to a router). Apparently this sync app uses this method for syncing the data. Normally it would be running over WiFi or LAN...but for some reason the OP wants to sync over an USB-cable.

The app does not rquire mobile data, but tethering., which in turn confuses Windows to use the shared mobile network for internet traffic, instead of WWAN.

Winfried · 2026-06-29T11:31:19-0400

Exactly.

Solved [USB tethering] Windows eats up my data plan

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