When you use homebrew to install php 7.1 it will cleverly install php-fpm which listens on port 9000. This is the default port for xdebug, so if you want to debug php scripts in a lando container, you will have some challenges.
TL;DR
If you've installed php 7.1 with homebrew, it listens on port 9000 so you will need to change the containers php.ini port specification to another port. e.g.
xdebug.remote_port=9001
Then tell phpstorm to listen on port 9001