I know how frustrating it is when you have a problem with your f5 and someone else posts that all is well with their device... but I have to say that my bluetooth connection is rock solid. I used a f3 for almost 3 years and the f5 connectivity is exactly the same. If I leave my phone (iPhone 6) on my desk at work, I know exactly where the connection drops off when I'm moving around the office, typically about 20m away from my desk, which is double the 10m spec.
I wonder if the problem is with a specific batch of devices?
Thanks for your input - since two weeks I'm struggling to decide if I should RMA my watch or not - Garmin support proposed RMA, but they ignored my question if they can officially confirm that there is some known issue with BT... I really want to avoid RMAing the device just to get another one with same behavior. From the other side - it can also be the phone causing problems etc. I really think Garmin should do better job in communicating known issues and status if they work on fixes.
I see you're on an Android phone? I remember seeing somewhere that an Android user fixed their bluetooth issues by unparing the watch with the GC App, then pairing it directly with the phone, not via the GC app. Is this something you've messed around with?