- Open Minecraft normally
- Go into a single player game
- When in the gameplay, open the menu and open the game in the LAN
- Note the port and maybe the IP
- Open the minecraft launcher so the current login tokens are getting refreshed
- Close the launcher
- Open Explorer and go to
%appdata%\.minecraft
- Edit the file
launcher_accounts.json
and change the red marked name - Open the launcher and open the file to play offline
- When the game is opened, you can turn on wifi again
- Choose "Multiplayer" and open the already opened game. Either it will be listed or you have to connect directly with
ip:port