Iphone 6's for use on att. I called att and they sent the carrier update to both devices. Both connect to LTE and make calls. However, in places that my 2 5s have LTE, the 6's are on "4g". I also did speed tests on all 4 phones in the same location and both the 6's have slower download and ping times. Any suggestions? I'm most likely going to return and purchase att versions.