Unexpected disconnects from phone (s24u)

Hi,

Is anybody else getting Bluetooth disconnected and then heave to re-pair when back in range by using the pairing code?

The message is something like "the watch has unexpectedly disconnected" and puts up a box to enter the code that is on the watch

It used to be occasional, but now it's every time I go out of Bluetooth range 

I have a Samsung s24u and have checked the app battery on the app is "unrestricted mode".

I have reinstalled the app from scratch. 

Not sure  what else to try.