iPhone 14 Pro 5G works only when Low Power mode is on

Kargian wrote:

Low Power mode, for the battery

That simply means the battery does not have enough juice to have both 5G and regular functions going at the same time. 5G consumes a lot more power than 4G or LTE.

So first check your battery health and charge level. It may be that you need a new battery. And yes, cellphone batteries don’t last forever, they are consumable and start deteriorating the day you start using them. If your battery health (not charge level) is at or below 80% you probably do need a new battery.

iPhone Battery and Performance - Apple Support

About the battery usage on your iPhone, iPad, and iPod touch - Apple Support

Just a guess, but I’d say that when it’s on low power mode the phone secretly uses 4G instead of 5G to save battery, but for user experience reasons keep the 5G icon at top so you know you have 5G available to you. When you turn off low power mode the phone actually tries to use 5G and then gets disconnected for whatever reason

Low power mode or Low Data Mode? I am not clear here.