Windows Media Player using Wingate

[cddo]

Our company have some TV program broadcast using windows media service. However, it has IP restriction which only company LAN users can view the programs. My idea is using VPN plus Wingate to cheat the server.
The process is that first use VPN connect to the company, make the IP to be member of the company LAN, and then use one company PC to install the Wingate as a Proxy server. When I config the windows media player to use that proxy and play the video, it reports something like "not available multicast". It seems that the media server uses multicast and wingate cannot handle this. Anyone have idea how to solve it? Thanks.