We have three Fitbit devices here at home (Surge, Charge and Charge HR) and before that we had a couple of Fitbit Flex. For the last year or so, every time I tried updating the firmware on these devices while connected to the Vodafone cable network they failed to update. Connecting to our backup network (2degrees Broadband) on good old ADSL usually completes the job.

The latest was yesterday trying to update the Charge HR - it simply stopped at 50% and froze. The device was bricked but Fitbit support told me to try updating again or removing/adding to the account again.

We tried this with no success. I then remembered how all previous updates for other devices failed on Vodafone cable. Disconnected my laptop from the LAN, connected to the Snap WiFi router and the update completed ok.

I suspect somewhere, somehow the Vodafone proxy is corrupting the update files for these devices.