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Perform following to update DocumentDB master user namecluster listening port:
Login to the AWS Management Console at https://console.aws.amazon.com.
Navigate to DocumentDB console.
On left Navigation pane, click Clusters.
Select database Cluster to configure.
Click on Cluster Actions and choose Modify.
In section Database Options, set Database Port to a non-default port.
Click Continue.
Click Modify DB Cluster.
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