Fitbit Flex no internet connection

[SJA69]

My husband's fitbit won't sync with his iphone app unless his wifi is turned on. Mine syncs fine through blue tooth without wifi. I think it's a fairly recent problem although not entirely sure as he hadn't used it for a few weeks. We've tried resetting the fitbit, turning phone on and off etc. There isn't the option to update the app through the app store as thought that might have been the problem. Any ideas?

[SteveH]

Could it be that you have mobile data switched on but your husband doesn't?

When you sync you need bluetooth on for the phone to talk to the fitbit and you also need either wifi or data services for the phone to talk to the fitbit servers.