Give us a shot of the Connection Status from your router's page. The details tell the actual connection you have, noise to the signal and how far you really are from the cabin. It is the first step to know check on you connection before testing it online.
In which point did they perform their test? Having it different than what you actually get, gives me a bad feeling.
Also, make sure no one else is connected/no background connection are there when you do the test.