I assume you mean for Data Backup??

Ive always just used 5722 however you can use any port.

When you are setting up private storage it asks for a port, the official answer to that is, The inbound port used to contact the storage server. Use any port number not used by another process.

To Create Private Storage

1. Select a machine in the middle pane.

2. Enter the following storage credentials:

 IP Address - The IP address used to contact the storage server.

 Port - The inbound port used to contact the storage server. Use any port number not used by another process.

 Backup Location - The drive and folder path on a storage server to store backups. The folder path must exist on the storage server. It will not be automatically created for you. Example: c:\databackups