In your Vagrantfile...
Forward a port from your host machine to 8000 on the guest. 8000 is the default port the grunt server runs on.
config.vm.network "forwarded_port", guest: 8000, host: 8094
Forward port 35729 on your host to the guest. 35729 is the port used by livereload: https://github.com/gruntjs/grunt-contrib-watch#optionslivereload
config.vm.network "forwarded_port", guest: 35729, host: 35729
In your Gruntfile.js use the
0.0.0.0 IP address to allow access from the parent machine & local machine: