Try a different browser. We recommend using Chrome, Edge or IE.
If you're using public wifi or some kind of public internet, you might get an "Error during negotiation" when you enter the lobby. That's because public internet often blocks required ports. Try different (private) internet connection.
If you're using Opera Turbo, that might be causing the problem with loading the game (getting stuck on the Loading screen).
Note any errors showing up in the chat (in red text). Copy/paste them to the Bug reports forum.
If none of this works, open Chrome developer console (F12, then switch to the 'Console' tab). Copy/paste any errors appearing there to the Bug reports forum.