I recently started playing and kept getting the connection refused. I searched everywhere but couldn't find the solution but found out myself. The issue is that for some reason when you start truckersmp it activates all the docs for the game (All dlcs are downloaded with the game just not useable if you don't own them). The solution I found is to go into the game file and delete all the docs you don't own. For the base game delete all the docs except all the trucks and Arizona and Nevada.