Once you have an UDP Socket created with Socket.NewUDPSocket function, you can switch it to broadcast most using Socket.SetBroadcast function.
Now when you send package to a broadcast address in your local network, e.g. 192.168.1.255, you send it to everyone in the network.
This can be useful in your FileMaker solution to send messages to another FileMaker Pro app in the same network. Be aware that UDP is unreliable. A solution can be to give each message an ID as prefix and send it three times with a little pause in-between. On receiver side, filter out the duplicates and process only new messages.
Will be included soon in 5.3pr1 plugin.