I'm assuming this is one of those "it's specific to your device and/or area" things that there's not much to try other than the standards and calling T-Mobile, but never hurts to ask. I've have an iPhone 6 pretty much since launch, and I live near a T-Mobile tower, so I usually have 4 or 5 dots of LTE signal at home and walking to work. Has been working fine and reliable. Until maybe the last couple of weeks. Now I still have the expected 4+ dots and LTE in the menu bar, but the phone has no data connection at all, or sporadically--Siri fails, can't load anything on the web, etc. Tried toggling Airplane Mode, no love, tried rebooting the phone, didn't make any difference. Congestion seems unlikely, since I'm on a campus tower and the problems have gotten worse since school let out for the summer, when the area is virtually empty compared to usual. I don't think it's my phone, since in a nearby town with the same 5 dots of LTE, it works fine and Speedtest shows a (to me) shockingly fast 45Mbit down and 11Mbit up--that's faster than my cable internet connection at home. The one thing I haven't tried is a full restore, but it sure seems like the problem is with the T-Mobile tower. Any suggestions other than calling T-Mobile to whine?