Some types of router software have the ability to adjust the power of the wifi signal or turn it off. I assume the neighbor is a friend who will allow you to log on and check.

the alternative is to turn off the wifi in that unit and connect a dedicated access point that has the ability to change the wifi power.

You could even get an old router and put one of the free or low cost software (firmware) options on it. Some of them have the ability to adjust wifi strength.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwij3OSh0q3lAhXnYN8KHRYnBhIQFjACegQICxAQ&url=https%3A%2F%2Fwww.techspot.com%2Fguides%2F416-wireless-router-custom-firmware-alternative%2F&usg=AOvVaw2NTOJeTQYqiVC3HSpAd9br