The Italian carrier TIM, Ericsson and Qualcomm have collaborated on a project to push millimeter-wave 5G reception beyond its current limits. This work has resulted in the ability to pick this signal up at high speed from 6.5 kilometers away. Then again, this was not done with smartphones, but rather with equipment for potential next-gen wireless broadband.
https://www.notebookcheck.net/Qualcomm-TIM-and-Ericsson-claim-the-new-long-distance-mmWave-5G-world-record.508046.0.html
I probably will newer get decent 3G-4G signal. Sometimes whit one second delay.
Whatever that cylinder is it's about the size of 20 smartphones stacked together.