I am using UDP multicast to send messages to an embedded host (Raspberry Pi) in my home network but I am running into issues receiving multicast traffic on Ventura 13.4. I have a simple Python receiver/sender script: receiver.py (with from_nic_ip set as the local address related to the port that I want to bind to, multicast addr: 224.0.0.0, multicast port: 42073) def receive_loop(from_nic_ip, multicast_group_ip, multicast_port): receiver = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM,\ proto=socket.IPPROTO_UDP, fileno=None) multicast_group = (multicast_group_ip, multicast_port) receiver.bind(multicast_group) if from_nic_ip == '0.0.0.0': mreq = struct.pack("=4sl", socket.inet_aton(multicast_group_ip), socket.INADDR_ANY) else: mreq = struct.pack("=4s4s",\ socket.inet_aton(multicast_group_ip), socket.inet_aton(from_nic_ip)) receiver.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq) while True: buf, _ = receiver.recvfrom(BUFSIZE) msg = buf.decode() print(msg) reciver.close() sender.py def send_loop(host_ip_addr, multicast_group_ip, multicast_port): sender = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM,\ proto=socket.IPPROTO_UDP, fileno=None) multicast_group = (multicast_group_ip, multicast_port) sender.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 1) sender.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF,\ socket.inet_aton(host_ip_addr)) while True: print("Sending data!") sender.sendto("test".encode(), multicast_group) time.sleep(1) sender.close() If I run macOS as a sender and the Raspberry Pi as the receiver, I get the expected output: "test" printed continuously. If I reverse the roles, I see no "test" output. I have verified that the script works as a sender/receiver by duplicating the test on a Linux desktop and I see that the two nodes can communicate with each other as both a sender or receiver.