Pebble Clock With Distance App

Stuck on 'Waiting to Reconnect' doesn't sound normal...

By default many Android devices do some very aggressive battery management which can shut Gadgetbridge down any time it's in the background (which is when you want it!).

Maybe you could check https://dontkillmyapp.com/ and see if you can do anything to stop Gadgetbridge getting shut down in the background - that could really help you.

now back on another phone and working within the same conditions

Not sure I understand - you're saying the connection is more reliable on a different type of phone, or the same?