Intel radio modem in our Asian model. Not very good. Heats up easily esp underground in train journeys. Never encountered that for my 6s+ last year.
Mine's under Singtel and depending on location, will sometimes go to 3G and sometimes to 2-3 bars signal. Else, will be full signal strength at 4G.
My only issue with the 7 Plus is that some time (intermittently), there will be no data traffic even though with full signal strength, and have to restart the phone.