Preferred ssl challenge to dns

v4
#1

In this handbook i found

but for some reason when i use the command :
sudo ee config set preferred_ssl_challenge dns
i get the error :
usage: ee (sub-commands …) [options …] {arguments …}
ee: error: unrecognized arguments: config set preferred_ssl_challenge dns

so …that wont work.
any other ideeas ?

#2