It’s Christmas there are having a well deserved rest like the rest of us. They will reply when back to work.
I have a feeling that something’s blocking multicast packers on Samsung devices. It seems lots of Samsung users on Android 11 seem to have this issue. I’m on 11 but on Pixel 4 and don’t have a problem. I wonder if this is part of the battery saving procedure to reduce unwanted drain so I wonder if there is layer on top of Android that is disabling WiFi MulticastLock to block the packets being received.