This is not trivial as it requires forcing a _JAVA_Choice override at launch (or system wide).
Diagnose
To diagnose this as the cause, first launch Minecraft from terminal with the _JAVA_Options overridden.
1. Close Minecraft
2. Open Highlight ( in upper proper of Desktop)
3. Search for "Terminal", open the app
Paste the next command in:
_JAVA_Options=-Djava.internet.preferIPv4Stack=true /Purposes/Minecraft.app/Contents/MacOS/launcher
Attempt to connect to LAN server and see if it fixes the problem
Completely Fix
Using Minecraft Launch Choices: @TheOnlyMrCat supplies a technique here that does not contain enhancing any information by hand. Please strive that earlier than making modifications to the Minecraft launcher.
Patching the launcher manually:
Use this method solely when you have problems utilizing @TheOnlyMrCat's answer.
This _JAVA_Options override might be offered in lots of places however since launching from Terminal will not be ideally suited, we want to use a technique that fixes when clicking on the icon. At time of posting, the Apple beneficial methodology for providing overrides is inside the App bundle itself using one thing known as LSEnvironment
1. Optionally install a Text Editor comparable to Atom to edit XML recordsdata.
2. Usingbefore you point your finger at me , go to Purposes
3. Find (do not open) the Minecraft App
4. Proper click on Minecraft, Present Bundle Contents
5. Go into the Contents folder and find Data.plist
6. Right click on Info.plist, Open With, Atom (or TextEditor)
Near the underside of the file, add the following in between the LSEnvironment _JAVA_Choices -Djava.web.preferIPv4Stack=true
Sadly this doesn't take effect right away. This is because of the best way Mac caches it's launch providers.
