I had been wondering for a while why my iPhone 7 Plus has had a weaker signal from AT&T than my 6 and 5 did, even though I'm in exactly the same spot near the same tower. My previous phones would show a solid 5 dots all the time at home, whereas my 7 Plus shows 2-3 dots, maybe 4 at best. The answer is band 30. The 7 Plus supports band 30, and the 6 did not. Band 30 penetrates less into buildings due to its higher (near 3GHz) frequency, so the signal strength will be less than other bands, even on the same tower. It took some experimenting with Field Test on two different phones swapping SIM cards and flipping airplane mode on and off to determine all this. Yes I'm a nerd, and yes I have too much time on my hands. So yeah, the 7/7Plus's reception is just fine! If you see weaker signal than before in some places, it's probably due to being on band 30. Interestingly, even though the signal is weaker, performance is FAR higher; I can push 80 megabits on band 30! So I'm not going to complain.