Why does my iPhone 12 go from 5G to LTE?

In a nutshell, because 5G uses a different spectrum than 4G LTE , it can deliver stronger and faster connections, higher capacity for traffic, as well as latency as low as 1ms.

Apple even says it takes into account your data plan: The default settings for 5G on iPhone are optimized for battery life and data usage based on your data plan. … However, inside the cellular settings, you can choose to turn 5G on/off on iPhone 12 manually to optimize for speed or battery life.

iPhone 13 models, iPhone 12 models, and iPhone SE (3rd generation) work with the 5G cellular networks of certain carriers . Learn how to use 5G cellular service.17 Mar 2022