When I use my Dutch original ISP IP address, I cannot receive AirstreamFM (http://airstream.purestream.net:9510/) on my two NP2500 Internet radios. However, using a VPN service and connected to a server in Luxembourg, that station can be received without any problems. So, I assumed that this station blocks broadcasting to the Netherlands. But, when I use a VPN server in the Netherlands, I can receive that station. That doesn't make sense to me. Anybody having any idea what could be the reason of this strange behavior?

Note that adding the URL to My Media doesn't help either.

Thanks in advance for any suggestions.