I too have a 64GB F755A stick. Everything used to work fine with all my devices. After upgrading to iOS 10 (currently 10.2) my iPhone 5s starts disconnecting ever time I try to access data on the stick using the SanDisk Connect Drive app. I can get as far as seeing the top level directory, but as soon as I try to open any file or folder, it always disconnects. Sometimes it takes a few tries to even get that far.
My iPad and my wife’s iPhone 6 are working just fine, using all the same iOS app versions from the latest updates. So it seems to be a problem unique to my iPhone 5s. I have tried rebooting, and tried switching to a static IP address as was suggested in another post, but neither helped.
