Mine also uses a separate fuse box which is connected to the main unit and it works just fineUnfortunately the power cable was interred 2 years ago when the cabin was built!!
The power cable way probably won't work as the line to the cabin is separate from the house system so I believe it won't carry the internet out to the cabin. ??
An ethernet cable would have to be covered and my fence is a bit ropey for attaching stuff to.
Order some PowerLine adaptors on Amazon, and if they don't work, send them back.Interesting!! Must try this! Will call Devolo.
Did you research the brand? No prices given own Devolo's website.
Do you have a landline out to your cabin? How could a phone be installed?
Thanks so much for your help.