I know a lot of people are having this problem, but mine is quite weird. I played the old MP mod when you had to downgrade to 1.12 and that worked fine (first time in fact) But now with this one, no matter which version I try, or how many times I reinstall the mod (or the game) it doesn't work. I uninstalled the base game and deleted the steam folder/documents folder. That didn't work. I uninstalled the mod at the same time (and deleted the documents folder) and that still didn't work.
Now here is the weird thing. I installed ETS2 on my laptop 2 days ago so it has only had the most updated version of ETS2 on it (unlike my desktop that has had older versions) I installed the MP mod on the laptop and it worked first time. I'm not playing on my crappy laptop just to play MP but I can't figure out why it works there and not on my desktop! Any help would be very appreciated.