Yes and no. let me explain.
According to Wireless Standards (Wi-Fi) no, That's about the max limit for a consistent and stable wireless connection. If you have environment variables, it can change (wind and rain, trees..etc) and usually for the worse. So that's why there's a no part of this answer.
The wireless signal works like the lifting strength of our arms. If we can pull up close our body, we can lift more. If I extend to my fingertips, I cannot lift as much. If I go any longer than that, just about impossible. After the max theoretical limit of Wi-Fi, the signal strength to reach beyond it must double to get just few more feet range. Once you start doing this, the FCC wants licensing because you may be interfering and need more power than the personal grade equipment.
Have said that, the strongest access points you can get for the legal limit are the EnGenius APs. You can search for them out there with your favorite search engine.
Yes. you can install a repeater. If you want to extend the range of your signal, you'll need to put a wireless repeater between 50 to 80% of the max range. This will allow your the shop to be reached but setting it up may require a bit more research.
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