I currently have an iPhone 12 Pro running on iOS 14.4. I’m currently up in Canada and roaming, but I’m not sure where this problem is unique to roaming. When I connect at LTE everything works as expected, but if I connect to a 3G network, I get the “Could not activate cellular data network. Turn on cellular data or use Wi-Fi to access data”. Here are some of the things I’ve tried:
- Reset Network settings multiple times
- Tried multiple carriers (Telus, Rogers, Bell), if on 3G same problem arises
- Tried an AT&T sim which allows me to roam on 3G on Telus. So I “believe” the phone isn’t the issue
- T-Mobile thought the Sim card could be the issue, so I removed the SIM and activated the eSim instead. Same 3G problems.
- When I had my iPhone 11 Pro, I never had any of the above issues.
- T-Mobile has also made this very hard to diagnose as they’ve disabled the iPhone 12 from turning off LTE. So I can’t force the phone to 3G. The only data settings are: 5G On, 5G Auto or LTE.
I’ve spent over a month with T-Mobile at this stage trying to debug this but haven’t made any progress. Any thoughts or recommendations here?