openvpn: ping only works between server and client

Notice to my future self:

  • an openvpn connection can be stablished between client and server
  • you can ping the server from the client
  • you can ping the client from the server
  • you added the route in your server config
  • route -n shows everything is in place
  • but you can not ping any host on an attached network

… then you forgot to add a file in the ccd-directory for the correct common name of your client containing all iroute statements.