one way you can check is by uninstalling and reinstalling the game. recently the game went through a few updates and this also helped me out. unless you already tried that lmao
I recently tried to play the game with a friend and it also wasn't working. Then we tried with a fresh build and it seems to have fixed the issue, even though I don't think I changed anything that should affect networking. I just uploaded that new build so that you can try it too.