Hi @Samuel Sefeen ,
all andorid mobile phone can't synchrozing with exchange and when i reconfigure their account on their phone, they work well without any problem
Since it works well after reconfiguring the account, seems to me that there should be no issue in the configuration on the server side. And as far as I know, actually modification in Exchange server side is limited in this scenario.
Have you tried restarting IIS("iisreset /restart") and see it can help?
Are the affected users using the same model of android mobile phones? If there are iPhone users in your environment, could you have a look at them and check if they are also experiencing the same thing?
Any luck powering off and turning on the phone again?
Besides, to double check if there's any error with ActiveSync, you can run a test using the Microsoft Remote Connectivity Analyzer via https://testconnectivity.microsoft.com/tests/Eas/input
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.