I have had the Moto Z since Thursday and it only gets 3G in my office building. In this same space, the original Droid Turbo had mostly full bars with some interior spaces having only one bar. Changing the network settings from Global to LTE/CDMA limits the amount of time the phone switches to 3G, but still has very low signal strength and network performance.
Why would this be happening? I would expect a newer phone to have better reception/antennas.