Alright so unfortunately these commands somehow manages to block completely the internet connection of the yunohost (and anyone else connected to that VPN). I am not entirely sure why. However, thanks very much for taking the time to try to help 
Also as a side note, based on what ljf wrote I also tried some of the postUp.sh commands from here that seems to be work a bit better, but I am beginning to run into the issue that all 443 traffic (including those that are going to other clients) also gets redirected. (I think)
To the risk of asking something stupid, is this supposed to happen?