Update (9/16): T-Mobile has informed us that the issue has been fixed. You can find more information here.
While iOS 10 is a great upgrade for any iPhone user, we’ve got a word of warning for T-Mobile subscribers.
Some users have dealt with connectivity issues after the upgrade. T-Mobile CEO John Legere, on Twitter, said a fix is coming soon.
Apple is working to resolve the issue with iOS10 for @TMobile customers. Don't download iOS10 if you currently use an iPhone 5SE, 6 or 6+
— John Legere (@JohnLegere) September 15, 2016
If you’re a T-Mobile customer and have already upgraded to iOS 10, there is a temporary fix if you run into the issue. You’ll need to do a hard reboot by holding down the Home and Sleep/Wake button at the same time until the screen turns off and the Apple logo appears.