The default behavior for the RealAudio Player and the RealPlayer is to receive data packets via UDP. Some systems behind packet-filtering firewalls cannot receive UDP packets.

In some cases, switching this default to TCP can solve this problem.

RealAudio Player 2.0 and earlier:

1. Select Preferences from the View menu.
2. Select the Network tab in the Preferences dialog box. The upper-most option is "Receive Audio Via" with an option of UDP and TCP.
3. Select TCP, and click the OK button.

RealAudio Player 3.0, RealPlayer 4.0, RealPlayer 5.0:

These versions of the Player automatically detect if you cannot receive data via UDP and switch to TCP. In some cases, you may need to force the Player to default to TCP.

1. Select Preferences from the View menu.
2. Select the Transport tab in the Preferences dialog box.
3. Click the Use Specified Transports box.
4. Click the Specify transports button.
5. Check the Use TCP for all content option and make sure that the other options are unselected.
6. Click the OK button in the Specify Transports window.
7. Click the OK button in the Preferences window.

For more complete information on firewalls and how RealAudio and RealVideo work with them, please search the Knowledge Base with the keywords "configure AND firewall".