I have a prototype Android app that is listening for multicast packets to 'discover' clients to communicate with. The socket set up is similar to this:
InetAddress group = InetAddress.getByName("228.1.2.3");
MulticastSocket s = new MulticastSocket(4000);
s.joinGroup(group);
This works very well when all the devices are connected via WiFi. I would like to support this with the phone acting as a portable hotspot. However, while all my devices appear to connect to the hotspot correctly I no longer receive multicast data. I'm wondering if there are restrictions that disallow this type of communication in hotspot mode, or if there are is any additional network configuration required to enable this? I've tried this on a couple different devices running Gingerbread and Froyo with no luck.