Article ID: 873185
When you try to connect to a remote Microsoft Windows XP Service Pack 2 (SP2)-based computer by using the AutoCAD File Transfer Protocol (FTP) service, you may not be able to open a project.
This behavior occurs because the remote computer that you are trying to connect to has Windows Firewall configured to block the AutoCAD FTP service. The AutoCAD FTP service uses TCP port 21. By default, Windows Firewall has TCP port 21 turned off.
To work around this behavior, turn on the AutoCAD FTP service on the remote computer that AutoCAD is trying to connect to. To do this, follow these steps.
Similar behavior may occur in other programs that use FTP to connect to remote computers that are running Windows XP SP2.