Microsoft KB Archive/839221

= User Datagram Protocol does not work with some firewall packet inspection routines =

Article ID: 839221

Article Last Modified on 11/17/2006

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APPLIES TO


 * Microsoft Windows Media Player 9 Series
 * Microsoft Windows Media Player 9 Series
 * Microsoft Windows Media Player 9 Series
 * Microsoft Windows Media Player 9 Series
 * Microsoft Windows Media Player 9 Series

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SYMPTOMS
When you use Microsoft Windows Media Player to stream media files over a network, the player may stop working after you try to connect to the media files. These media files can include music files or video files.

Sometimes, you do not receive an error message or any other message that indicates that a problem has occurred.

Note This problem does not occur when you play local media files.



CAUSE
This problem may occur if a network router or a firewall is blocking packets from the server computer that is running Windows Media Player. Some firewall inspection routines may block packets from the User Datagram Protocol (UDP) data stream.

If either the router or the firewall blocks either the UDP data stream or the acknowledgment of the client request by the server, Windows Media Player tries to make additional connection requests to the server that is running Windows Media Player. When no valid information is returned, Windows Media Player stops responding.



RESOLUTION
In some instances, the hardware manufacturer may have a firmware update that corrects the problem. For more information about firmware updates, contact the hardware vendor as described later in this section.

Content providers can also author links so that the player tries to roll over to an alternative URL when Windows Media Player does not make a connection. By using failover in the client side ASF Stream Redirector (ASX) file, a content provider can help make sure that you can connect to a stream, as shown in the following code:  For more information about files that use the ASF Stream Redirector (ASX) file format, see the Windows Media Player 9 Series software development kit (SDK).

For information about how to contact the hardware vendor for your equipment, click the appropriate article number in the following list to view the article in the Microsoft Knowledge Base:

65416 Hardware and Software Third-Party Vendor Contact List, A-K

60781 Hardware and Software Third-Party Vendor Contact List, L-P

60782 Hardware and Software Third-Party Vendor Contact List, Q-Z



Additional troubleshooting steps
 Make sure that media files on the local system play as expected. Connect the client computer directly to the local network or to the Internet. If the remote media files or the remote sources play correctly after you complete these steps, the cause of the problem is probably the router or the firewall. Turn off the UDP protocol feature in Windows Media Player. To do this, follow these steps:  On the Tools menu, click Options, and then click the Network tab. Under Streaming protocols, clear the UDP check box, and then click OK.</ol> </li> On firewalls or routers that support the UPnP functionality, make sure that the UPnP functionality is enabled.</li></ol>

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Keywords: kbprb KB839221

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