Our members have been informing us of a hotspot settings problem with iOS 7.1, used on iPhones and iPads. Specifically, when they upgrade to iOS 7.1 they lose the APN settings from their operator. This is an international issue. We have confirmed this problem on the Apple Support Community. It apparently only affects certain iPhone devices, such as the iPhone 4, 4S, iPhone but not the iPhone 5S.
We understand the problem will be solved with the iOS 7.1.1 version.