I had quite some trouble getting a network access for my OpenSprinkler. The box is placed right under the surface and while the WiFi is just good enough at surface height its no longer reliable a few centimeters below. Then I wanted to use Power Line which sounds like a good idea as the OpenSprinkler has to be powered anyways (might be a nice option to be ordered in the future, eh?). Unfortunately when connected to the socket right besides my router it could connect. So I had to use a socket in the garage which is nearer to the outside placed Power Line adapter in the garden. I used a WiFi Bridge to connect the Power Line adapter in the garage.
I never thought it would be that hard to get a connection but you don’t install an ethernet cable in the garden “just in case”.