Seeing cameras away from home wlan

I have a zmodo 4 camera nvr.
All 4 wireless cameras are set up and can be seen on an android phone on the same home wlan.
But nothing can be seen on the same phone when I am away from home on a different Internet connection.
What do I need to do to be able to see the camera output when I am away from home? The home wlan is behind a router and obviously stops me from accessing the cameras when outside the home wlan. I know very little about networks. So please help.
Thank you

Use the Zmodo app instead of the Zsight app

I was also have same question. That @Patty for the reply.