muticast on wireless routers?

[moogie]

Last night i made a little tool which uses UDP multicast to share files in a LAN setting. This tool is to replace the bottle neck of copying a file from 1 computer to many such that now only one computer sends the file and the others listen for it.

For a time i thought that my program was fundamentally flawed as at most i could achieve was ~100 kbps

I then unplugged the test computer from the Dynalink rta1025W router and put it into the generic 100mbit switch i had lying about... using this generic switch i was getting ~10megabytes a second.

So either it is a "feature" of my wireless hub to make multicast through put extremely slow or it is a natural byproduct of WANs.

If it is the later, is it possible to configure a wireless router not to send udp multicast packets over the WAN and restrict to only the 4 wired lan ports? What settings should i be looking for in the the router setup?

Any help is appreciated.