You have 5 routers + the Telus gateway and you're trying to cover 12 acres of land??? There are so many possible things that could be causing issues it's hard to even say where to begin. If you have merely connected each router to LAN1 on the previous one, and you haven't changed the settings on all of them, they could easily be fighting each other.
Here is my suggestion, though @Nighthawk may have a better one:
Note: long runs may require an intermediate device to boost the signal.
Beyond that, you are looking at a commercial installation as previously suggested.
Option 2 - Access points
To clarify, are you just trying to reach the living quarters? How far is it on your property? Or are you trying to have wifi on the entire farm?