LES1 and iPhone - BLuetooth Problems

Hey,
I want to use my LES1 with my iPhone6s running iOS11, but every time the bluetooth connection is lost and it reconnects it wants a new pairing code.

Now I have the Custom BT-Calling Firmware installed It works good but wenn connection lost i musst go to the settings page of the BT-Calling app then it reconnect automatically.

If the connection  interrupts I do not notice anything so the watch doesn´t receive any messages and calls till ich see it and reconnect it manually.
Is there anyway that it works in the background and reconnect automatically ?

Sorry for my bad english

THX RunningX