Bluetooth re-connection problem of my Garmin Fenix watch after been out of reach of my iPhone

hey there, 

since some time I got some problems with my bluetooth connection which I never expirienced before.

The connection from my Garmin Fenix 5x Plus Watch to my iphone X is stable as long as my phone is more or less in reach of the watch, but sometimes ist happens, that after I went away from the phone, for example to a different room and the watch lost the connection that it will not automatically reconnect, when I‘m near the phone again. Disabling and reenabling bluetooth on the watch does not help, I need either disable and reenable bluetooth on the phone or go into my devices list on the phone and open the connection manually by tapping on the device name.

I have the latest firmware installed on my Fenix 5x Plus as well as on my iphone and I was not able to determine yet, why and when this problem happens. I have the feeling, it happens more often when I‘m away from the phone for a longer time, for example half an hour. But it does not happen always and everyday, sometimes it does not happen for two days and then twice or three times.

I also did delete all the garmin apps from the phone and also deletes the bluetooth connection and setted up everything from scratch, without any luck.

I read several threads about bluetooth problems but I‘m not sure, if this relates to my problem and I‘m also not sure, if the problem is on the watch or the phone side. I rather tend to believe it has todo with the phone as toggling bluetooth on the watch has no affect, also restarting the watch does not help, I really need to reset bluetooth on the phone or start the connection on the phone manually......and it seems it has started with one of the more recent IOS updates. Maybe there was some timeout for bluetooth LE connections implemented?

Anyone got a clue or similar issues?

Greetings

Bernhard