Tried it today with an Eon Core and customization with the app works for me Do you still have ossues?

@Nico78 There’s no “classic” bluetooth. Suuunto watches (and most wearable devices) use low power edition of bluetooth (btle) on all suunto i believe it could be 5.x edition minor number doesn’t make sense. it works on the same band 2.4 GHz. but significantly lower transmition power ±0.1 W as far i remember depends on exact antena and case.

allrighty then… back in business #fingerscrossed Trying to factory-reset the watch while battery left, did not work. It always crashed and restarted before I got the chance to cycle through the menu to that option, also button-press did not work. Let it drain power. charger (USB-C) was connected to a docking-station, placed watch onto charger… charging icon appeared, followed with the bootup of the watch… did not follow it all the way through, but ‘green firmware restore’ screen were shown when battery was sufficient (3% ?)… let it lie for a bit and started with black screen… as already noted in earlier post, the watchface is non-existent, black screen… pressing the crown (middle button), my ‘Sun-up / Sun-down’ secondary screen is shown… pressing ‘back / lower button’ returns to the non-existing watchface screen… turning the crown to ControlPanel > Settings > General > Reset settings , it stated it needed 40% battery before doing so… Not sure how come, but leaving it on the charger kept the menu’s scrollable, and the watch did not crash ! Waited till 40% battery and did ‘Reset settings’ … Watch displayed that it would turn off, and crown-button press needed to be used to boot-up again… it did not… After these messages, it reboot and started restoring the firmware screen once again… uhoh… but… it was one continuous cycle where the green progressbar slowely filled and when 100% full, the watch booted and all initial questions on eg. age, length, metrics were presented… Opened Suunto App and reconnected the watch… after removing the old device on my iphone, otherwise it will not pair ! (bluetooth menu, ‘Forget this device’) So now I have a fresh device that is working as expected (for all I can discover for now)… Only nuisance… need to recreate all my custom workouts Will take it for a 'move ’ this evening and see if it holds up. Cheers @dimitrios-kanellopoulos , if anything is unclear, feel free to follow-up.