Oops. A carrier settings update, associated with iOS 10, is causing some T-Mobile customers to lose their cellular connection in places where they normally have a signal, according to complaints on Apple's support forums. AppleInsider says it’s confirmed the glitch.
T-Mobile CTO Neville Ray posted on Twitter that Apple is "working to fix an iOS 10 problem" within the next 48 hours. Until then, T-Mobile customers with an iPhone SE, 6, or 6 Plus are warned not to upgrade to iOS 10.