Exchange ActiveSync Redirect not working for Android device
It might happen that a mobile device running an Android operating system ist not being redirected properly by Exchange ActiceSync, when the mailbox has been migrated to Office 365.
Clear AutoDiscover Cache
When you change AutoDiscover settings for users, it can take up to 2 hours until the cached data is invalidated and the new AutoD configuration is sent as a response to new AutoD request.
Restart AutoD Application Pool across servers
Restart AutoD AppPool across Exchange Servers to clear AutoD cache.