We couldn't get any signal in our first room at BLT - not even enough to run the MyDisney assistant. Apparently BLT is pretty well known for wifi issues because of the curved shape of the building. We didn't have issues at the Poly or AKL. I know they're deluxe hotels, but since we did specifically have a problem with wifi, I thought it was worth sharing our experience.
We ended up being moved to a room closer to the lobby and the signal was fine there. I agree with the previous suggestion that it might be worth putting in a room request specifically for this. Closer to the lobby is probably going to be better for wifi. Maybe follow up when you arrive. And if the signal is bad in your room, don't be afraid to request a room change if it's possible.