snap – Postman installation error on Ubuntu 18.04 : api.snapcraft.io: no such host


I tried to install Postman on Ubuntu 18.04.5 LTS using snap and I got this error :

sudo snap install postman
erreur : cannot install "postman": Post
          https://api.snapcraft.io/v2/snaps/refresh: dial tcp: lookup
          api.snapcraft.io: no such host

Also tried to download the bin from here, but does not work too.