The trouble is, there's too much on 2.4GHz these days. When I first got it - 6 or 7 years back - my wi-fi reliably went from the front of the house to the bottom of the garden with no special aerials. And that was using a laptop that is relatively "deaf" compared to newer devices.
But with no changes to my setup, this range gradually eroded to the point that I couldn't get wi-fi in several rooms of the house, let alone the garden. Didn't really bother me, but I bought the wife a tablet, and suddenly wi-fi became upgraded in her mind from "that geeky thing I don't understand" to "essential service"
I tried a couple of different routers, but they were no better than my original. I still have and use it, and believe that it is performing the same as it did when new.
What has changed, however, is the proliferation of wi-fi networks around here. Back then, there was a total of about 6 that I could pick up. Now, there's more like 30 or 40!
To fix the problem, I bought a dedicated WAP and installed it in the most central part of the house. That made a decent difference, and so far, I haven't had to lie about where in the world it's based to get the last few dB from it...
There's every chance your experiments would have worked a few years ago, but I'm not really surprised that you're having trouble now. A friend of mine got about 5 miles line-of-sight with a high gain antenna when wi-fi was new and rare. No chance today, sadly.
How about tethering your mobile - is that an option with your device?