Multicast messages received for ports other than port 0?

I’ve written a plugin that has a UDP receiver class in it. The receiver class can accept both UDP unicast and multicast messages. I’m running into a problem receiving the multicast messages, and I think I may have found the problem. The messages I’m trying to receive are coming across the multicast IP address “” and port 15. I’m setting up my UDP receiver with the following call:

FSocket* Socket = FUdpSocketBuilder(TEXT(“multicast”))

The socket is built without errors, but I never get a callback from the FUdpSocketReceiver that I bind to this socket. Running through the debugger I found that in the Build call for the FUdpSocketBuilder class, the .BoundToPort(15) call is being ignored when a socket is joined to a multicast group. In the Build call, the following code is performed:

Socket->JoinMulticastGroup(*FIPv4Endpoint(Group, 0).ToInternetAddr()

So does Unreal only support multicast messages on port 0? Multicast messages should be allowed on any port specified.

Thanks in advance for any help you can give me on this!

i am using “GitHub - getnamo/udp-ue4: Convenience UDP wrapper for Unreal Engine 4” link for udp plugin, but i have no idea how to set it up and use it. maybe the instruction on the link is complete, but i am missing something.
i have just created a blueprint class and i want to use udp plugin to control my simulation with PLC, but i have no idea how to set the connection up