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macrumors newbie
Original poster
Nov 21, 2019
Happy post new-iOS version drop day.

Please do not repeat my folly: Disable hotspot mode on your iPhone if you aren't using it.

Here is my tale of woe:

I connect my iPhone Xr to my PC to do a full backup prior to the software update. Then I hit download new iOS version iTunes. A half hour passes.. Geez. This is sure taking a long time for iTunes to d/l. Then I get a text message on my phone from my carrier: "You have used 50% of your mobile data." :confused: That's weird. I rarely if ever do that. Oh well... Then 20 minutes later, I get one: "You have used 80% of your mobile data." Then it dawns on me: MY COMPUTER DOWNLOADING IOS 17 IS USING MY IPHONE'S MOBILE DATA!!! :eek:

Panic-disabled the hotspot mode on my iPhone - which also killed the download. After restarting the download on my home Internet, it took 5 minutes to download and start the install...

What are the damages? I have used 5.5 of my 6.5GB mobile data for the month, one week into my billing cycle. 😩

Did I miss the warning signs? Yes
  1. Windows Task Manager showed all of the activity going through "Apple Mobile Device Ethernet", instead of my regular Ethernet.
  2. The green hotspot icon present on my iPhone.
  3. The first 50% data-used text.
In my defense, I'm only half-paying attention while working... Last time I used mobile hotspot might be a year ago? I just never turned it off... And plugging in the USB cable evidently tells the computer and phone, "Come on in! Use my mobile data!"

tl;dr Computer will automatically start using phone hotspot when a USB cable is connected if the feature is turned on.
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macrumors Penryn
Aug 31, 2011
Aside from the fact that my plan includes unlimited data and 7GB hotspot data (some on my plan have 14GB hotspot), this is not anything I ever leave on.

I work from home and even when I didn't, my job (graphic design) involves computers which are hooked up to the internet. So, at home or work there is rarely ever a need to use hotspot (hence it's off all the time).

I did use my cellular data to download the over 2GB update on my phone itself the other day, but with unlimited data and deprioritization at 50GB of use, this is a drop in the bucket.
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