There may be an issue with the account that is used to connect to your Active Directory.
The Directory Service connector that is used to connect Amazon Chime with your Active Directory uses an AD account and often this user account’s password needs to be reset every 90 days.
Request that your AWS administrator verify the credentials provided in the Connector account tab on the AD Connector Details page. The user’s password may have changed or is locked out because it needs to be changed.
Below is an example of what the Directory Service Details page might look like: