Some players are currently experiencing issues connecting to multiplayer.
We are actively investigating the cause, but in the meantime, here are some possible solutions:

• Change Download Region
  Setting the Steam “Download Region” to the same as the person you're playing with may help resolve the connection issue.
  How to set: Steam Client → Settings → Downloads → Download Region

• Reinstall the Game
  Uninstalling and reinstalling the game may resolve the issue.

• Update the Steam Client
  Updating the Steam client to the latest version may help resolve the issue.

We sincerely apologize for the inconvenience.
We will continue to investigate and address the issue.

Thank you for your continued support of MustScream.