Using ng serve --host 0.0.0.0 will allow you to connect to the ng serve using your ip instead of localhost.
EDIT
In newer versions of the cli, you have to provide your local ip address instead
EDIT 2
In newer versions of the cli (I think v5 and up) you can use 0.0.0.0 as the ip again to host it for anyone on your network to talk to.
As a side note
Make sure your connection is set to Public in your OS settings.