I'm glad MacRumors brought this to attention. For the past week and a half, right before getting my 6s I started noticing incredibly slow speeds while on my home's WI-FI and over AT&T's LTE, but only when trying to download any updates or anything from the Apple Store, iTunes or Apple Music (streaming and downloading content for offline use). This happened on every device in my home, Macs, iPhones, and iPads. Strangely, internet speed tests were showing normal download speeds. In fact, Netflix, Hulu, and every other web page, including those from Apple, worked and still work perfectly fine on every device. However, if I leave my house and connect to the public wi-fi at the nearby cafe, any content from Apple Music, the Apple Store and/or iTunes download at perfectly normal speeds.
So in my case, its not only AT&T's LTE that is giving me problems, is also my home wi-fi, but only on Apple content. At first I tried using the phone as a hot spot, then modifying settings on my house modem to open DNS, etc. No change. I ended talking to the Cable Company and they even substituted my old modem for a new one. Still no change. I then spent an hour with the technical guys from the Cable Company, and in the end they blamed Apple servers. I also spent an additional hour with Apple on the phone, and we agreed that it points out to a Cable Company issue. However, why does it work as it should at the nearby cafe? And why does Netflix, Hulu and the rest stream just fine on LTE and WI-FI?
Any suggestions would be greatly appreciated.