"Network unstable" ¿what i can do to fix this problem?

Tested with a friend and he got the die 5 times achievement in the achieve tab in the game, but did not get the achievement on steam.

The game is like a freezed image and is not playable.

everytime I launch the game it always says network error

I cant join to the game "network unstable" nobody help me and i dont know what i can do to fix the problem