I suffered from the same issue and after a week I figured a workaround.
Problem: when you connect to the drives wifi, your iOS 10 devices tell you it’s insecure public network and it hasn’t got internet. When you open Connect Drive app, it won’t connect to your wireless connect drive
Workaround: DO NOT use DHCP up address, use Static IP address instead. Press the power button for 15 seconds to reset your drives setting, once it’s reset connect to the drives wifi - do not open the app just yet (very important). Mark down your DHCP details - IP address, subnet mask, router, and DNS, and copy all these details to Static IP setting and use Static instead. Then you can open the app and enjoy
Hope this helps