Fenix 5S+ loses Bluetooth connection with iPhone

Hi,

My watch is constantly losing the Bluetooth connection during the last few days. When I check the settings in my watch it says that it waits for my phone. When I turn the Bluetooth off and on again it asks me to open the app on my phone. Sometimes it reconnects but most of the time I have to restart the phone.

There hasn't been an update on the phone or the watch. I did change from provider but I can't imagine that it can cause this problem.

Can anyone help me with this issue?

Thanks in advance!

Gon