Personally I had issue on host side, couldn't properly enter port and when confirming, game froze and eventually crashed. It is definitely something system specific since it worked for you guys, it just sadly might be relatively common. If I can help you somehow determining what caused the issue on my system let me know, game looks fun from screenshots :). PS: I've made sure that game is allowed by firewall.
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We would love to get insights on why the game is crashing on your system. It would be great if you could try to compile the game locally:
https://github.com/Heartbit-Interactive/MGJam2021