Mobile data not working on my girlfriend's iPhone 16 Pro Max after swapping SIMs

FrayBenthos wrote:

Thanks for speedy response. She has been using a VPN, but turning off doesn’t change things.

We’ll try resetting network settings now.

HOLD THE PHONE!! New info!

Uninstall the VPN completely and ensure no profile exists in Settings, General, VPN & Device management

Then try again.

Try resetting network settings. It will delete stored network passwords. So, copy or backup any network password that you may want in the future.

Reset iPhone settings to their defaults - Apple Support

Does she use a VPN?

Yes, do as LD150 suggests. Remove VPN, not just turn off. Reset network settings after removing VPN app and VPN profile in Settings app.

PS after SIM swapping always do this

Change of SIM or number. do all 6 steps here, don't miss any out

1.    Settings, Apps, Messages, turn off iMessage   

2.    Settings, Apps, Facetime, Turn off Facetime,   

3.    Power down the phone

4.    Turn on the phone again 

5.    Settings, Apps, Messages, turn on iMessage,   

6.    Settings, Apps, Facetime, turn on Facetime

 Then ensure your correct number appears in the Send & Receive

FrayBenthos wrote:

.. We just swapped SIMs and the problem continues on her phone (but my phone is fine with her SIM).

..

I have a different interpretation

Although SIM swapping can is not recommended without some tricks to initiate imessage etc, nevertheless you seem to have proved a problem in her phone.

You may have difficulty getting a warranty claim away from the country of purchase, but a repair does seem necessary to me

FrayBenthos wrote:

My girlfriend and I each bought iPhone 16 pro max 6 months ago. We use the same network and have identical settings. All was fine in the UK but 4 months ago we moved to the Cayman Islands, where we both purchased local eSIMs. While texts and calls were working on her iPhone, mobile data never did (although it was fine on mine). We assumed it was a local network provider issue but as we only needed one ‘phone, we waited until we were back in the UK (assuming that it would be fixed). We were wrong. Everything else is fine, she has full data allowance, WiFi is working but mobile data is still an issue. We just swapped SIMs and the problem continues on her phone (but my phone is fine with her SIM).

Factory reset and then return it as faulty, or is there anything less drastic we could try first? Thanks in advance, FB

[Re-Titled by Moderator]

Original Title: My girlfriend’s iPhone 16 Pro Max mobile data stopped working and mine is fine. We have identical phones, networks and settings, and even swapped SIMs. It’s definitely her phone. What could the problem be?

she'll need to work that out with her mobile data provider.