Help with web audio/video streaming using WLAN connection

I�m having problems getting streaming to work using the WLAN connection. It works fine with a packet data connection (BBC news for example), but times out on the WLAN. I�ve changed the access point in the Realplayer setting to the WLAN. I�m not blocking any ports on my router�s firewall as far as I know. Any ideas what it could be?

Thanks.