Question about myStrom Smartplug

Ok, what if I don't have a WiFi signal at the external socket because the distance from the router in the house is too great?

Yes you can, and as mentioned below, it must be protected from rain and damp. The connection is made via an application and the plug must be connected to WiFi for remote access outside the home.

Ja, per wifi

Yes, it's just not meant for outdoors... if not protected, e.g. under the roof, a waterproof cable box will help.