Before you start telling me to reinstall Minecraft, change wifi connection, disable firewall and antivirus, etc. it doesn't fix the issue, I've tried everything. And I've came to conclusion that all of my ports are closed. BUT i think it's something else, so... When I'm playing on normal(default) world I can "play" for about 3-20 sec, before getting disconnected with this message:

 ^{"Connection Lost Internal Exception: java.io.IOException: An existing connection was forcibly closed by the remote host".} 

But when I create SUPERFLAT world, this does not happen at all, I can play forever without getting kicked.

HELP ME MOJANG WHAT IS WRONG WITH YOUR GAME???