I'm posting on behalf of my S/O, who lives across the country from me, so I cannot provide the normal requested info.
She is using military WiFi on an Army-issued MacBook Pro, and due to distance and concrete walls, is getting terrible reception. She cannot just use a better receiver, since she doesn't have access to install drivers or utilities on her laptop.
I don't have any experience with extenders or boosters, so I can't recommend anything for her myself.
What is the best way to boost her connection?