Friday, April 7, 2023

Carrier-Forced Wi-Fi Offloading


Essentially, the latest iOS (16.4 at post time) allows your cellular carrier (via eSIM) to add “managed networks” to your device.

These networks cannot be removed, they cannot have “automatically join” disabled, and they have equal priority with your real, personal networks.

So guess what happens when your neighbors get a wifi/modem combo that blasts a free hotspot SSID? Not only does it pollute the already crowded 2.4ghz band, your iPhone will often prefer this connection over your real /local wifi (despite said wifi being at 1 bar).

As of post-time, there is no way to remove these networks short of completely disabling cell service/removing the eSIM and resetting all network settings.


Wifi offloading is not new. AT&T helped invent these standards back in ~2009 when their network was getting crushed by massive increases in traffic as iPhone usage took off.

WiFi offload networks are configured as “Managed Networks” which are lower priority than any user-selected networks. You can disable them by turning off “auto-join”. (Also these WiFi offload networks are secure; you can’t spoof them).

However it appears that the original poster’s carrier (presumably Xfinity Mobile or Spectrum Mobile) has done something new - they’ve disabled the user’s ability to turn off “auto-join” on iOS. Some overzealous team is trying to lower their cellular costs. That’s because both Comcast and Spectrum rent capacity on Verizon Wireless towers, but their MVNO cellular service is not profitable unless their customers are using the cable company’s own WiFi fairly often.


I noticed this a couple days back at Home Depot, of all places. Was looking up the locations of stuff I needed to pick up via their website while sitting out in the parking lot and my iPhone kept switching off 5g to hop on some single bar wifi that I couldn’t delete or deselect auto-join.

Eventually just turned off wifi and the problem was “solved” but man this is going to be annoying if it starts happening at the grocery store or something.


2 Comments RSS · Twitter · Mastodon

Dan Shockley

I know that normal "Disable auto-join" setting is not honored by Managed Networks.
It used to be you could go into Settings >> Wi-Fi, click the Edit button in the upper-right corner.
Then, scroll down the list of networks to the very end.
There, you will see "Managed Networks".
If you click the info icon ("i in a circle") on the right next to a network, you can turn off Auto-Join for that specific managed network.

But, apparently that only sticks for a few minutes in at least some cases. The first link above has folks theorizing that the settings re-sync with the carrier to turn Auto-Join back on.
Makes me want to wait to update to 16.4, since I'm still on 16.3.1, and I don't think this override-the-user "feature" exists for it.

So according to Reddit this might be a problem on Tmobile as well, which is a major carrier. And seems to be iOS problem only from reading the parent thread comments…

I don't have a new Android phone to test, sorry (my partner does have a Pixel 6a, so I can ask her next times she is at a known T-Mobile participating location), but my Samsung S10e does not have this problem as far as I can tell. It definitely has the Hotspot 2.0 setting enabled, but I don't have any saved WiFi networks on my phone and I have never been prompted to join one. Pretty sure I have to click the network when present and it will then connect with the SIM based authentication process.

To clarify on my end:
Hotspot 2.0 can be toggled off completely in settings if desired.
I do have the Hostspot 2.0 setting enabled.
I use a regular physical SIM, not eSIM (not even sure if the S10e even supports the latter).
I am on Android 12, not Android 13, in case this is a problem on newer versions of Android too, but it doesn't seem to be.

My questions:

Is this truly iOS only problem?
If so, does it depend on version of iOS?
Does using an eSIM vs traditional SIM make a difference in this behavior.
Shoulnd't the behavior still allow for customers to disable?

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