Computer nerd here. From the description of the buildings, and space inbetween, like @socrates mentions most "wifi extenders" are simply going to work like crap. Esp anything labeled as an "extender." 80% of those products are underpowered trash. Anything worth it is expensive. A practical, and cheap solution: Run a length of 10//100 ethernet to your office, buy an actual quality router and put it in "repeater" (aka, "Access Point" mode) mode in your space. (It doesn't sound like your relationship with your neighbor is up for that kinda work though.) There's a small chance that with a quality wifi router could be installed in your home against the wall closest to his building (w/o a cable run) also put in AP mode, could "extend" that signal. But I wouldn't bet my business on it. I promise you, anything else is going to be a waste of your time and/or money. I can't tell you the number of frustrated customers that I've dealt with, insisting on getting those "extender" products no matter how much I try to tell them don't.