I have used OSC just a few times now and I remember reading something like that too. I’m not sure what exactly they meant though as you always need to enter an IP address and a port to send your data to and that can typcially only be one client. Maybe something to do with multicast?! I don’t know.
I know one way to send to multiple receives though but I cannot recommend using it for all data you’re sending because that is effectively flooding your network with unnecessarily many packets.
Once I did have the need for communication without knowing the server IP address beforehand too. My approach was to send a first OSC message to a network broadcast address (sending to everyone on my network) and in that message I included the senders IP address. Everyone receiving it can then respond to that specific address and if they send their own IP address the original sender now knows where to direct messages to aswell. I got my local networks broadcast address from a function in Unity (I wrote software for android and windows in Unity) but you could enter your address manually. You can read up on broadcast addresses on Wikipedia: https://en.wikipedia.org/wiki/Broadcast_address
Your address might look something like this: 192.168.0.255
You can read a bit about it and if it’s your own network you could also test spamming it if you want to.
If you have any questions feel free to ask but I personally am gone for today and will have to get back to you tomorrow. Have fun 