Ip camera question

Hope this is correct forum, and please help me explain and offers a fix for my ip camera access issue.

I can access my camera iphone app from outside but not from the home wifi where the camera connected because I use wan ip.

70.80.80.80:90000 (example of my public ip) and I used UPnp for port forward 192.168.x.x:8080(Lan) camera ip

When I am in same subnet I need to use 192.168.x.x to access my camera. Then when I am outside I use public ip. How I setup my network so only use WAN ip to access my camera regardless where I am?

Thanks.