iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
iOS 7.1 Causing Issues With Personal Hotspots
While information can be entered into the APN fields of the Cellular Data Settings menu, the values do not save, and attempting to establish a tethered connection results in an error message. Apple's Support Communities currently features a 15-page thread on the issue that was started shortly after iOS 7.1 was released, with many users reporting the same problems with tethering.
Apple's support staff appears to be confused by the root cause of the issue, with several customer service representatives suggesting the problem lies with carriers. Carriers that have been contacted have indicated that it is an issue with Apple, however.
Same here. Hotspot not working since I upgraded to 7.1. Such an annoying issue. I phoned my carrier this morning and they didn’t want to get involved since “it's a device issue since settings can’t be saved". No carrier updates either when I installed 7.1. So right now, no hotspot and no one wants to get involved.Other users have heard that it is a problem limited to carriers that do not currently have a contract with Apple. The iPhone 4, 4s, 5, and 5s all appear to be affected by the issue, and there is currently no available fix. Users in Germany, India, Austria, Spain, Serbia, Thailand, Estonia, Hungary, Belgium, Italy, Brazil, and more have reported issues with hotspots.