i really do not have knowledge about the Multicast thing, but my Wifi Signal is good. And i used SAMBA and other wifi file sharing apps and they all worked using the same wifi.
And clicked RELOAD many times but i cant see any device in the popdown menu..
Mine didn't get detected right away either. I left the PC client open, as well as the phone app. Then I accessed my routers setup through my web browser, just looking for some options for multicast, and I noticed that the PC client had my phone in the list. I don't know if it just needed some time, or if it was from accessing the routers settings, but give that a shot.
I'm running a linkysys E4200, win 7 ultimate x64, and an HTC inspire running AR 7.0.2.
The router may have multicast disabled also. Google your router for it.