Minecraft – LAN world not showing up

This is a problem I also have when trying to play LAN with a mac and a windows 10 computer. When the mac hosts, everything works out wonderfully. When the windows 10 pc hosts, the mac can't find the LAN world. Here's my solution.

First, host the LAN server on the windows 10 computer. There should be a port given in the chat. Remember it. Then left click on the network icon in the lower right corner of the screen, and press "Network settings". On the screen that pops up, press "Advanced options". Scroll down through the properties until you get to the IPv4 address. There should be four numbers separated by periods, similar to this: 192.189.54.78. Remember them.

Now open up your Mac's minecraft. Go to multiplayer, then direct connect. Fill in the address with the IP first, then the port, like this: 192.168.54.78:56234

Then press Join Server, and you're good to go!

So I've done some testing on my side on a Windows machine, and this should be the same on all systems from what I've seen online.

I've setup two machines, with Minecraft on both PCs. I've also installed TPCView on both machines to view the network connections they create and leave open. What I've found that is Minecraft does not use it's own PID when making a network connection, but instead has Java handle the network calls.

From my personal PC, Java opens and connects with 6010-6127 onto a process locally. (Most likely this is to the Minecraft Process, except the red one which is Amazon's cloud services) When I click into the Multiplayer tab, we get four new connections, but two of them (UDP 4445) are left open:

I've tested this on the other PC, with the same outcome. four new connections, two of them matches the port that the game reports (60xx), and the other two are UDP 4445 left unconnected.

On searching about this, I've found a post from 2012 about a plugin author making an app to make local worlds announce themselves as LAN worlds using the same UDP 4445 "Announce" port. I would have to believe that this port (UDP 4445) is the one that is being blocked from allowing the game to announce it self as a "open server" locally.