That should be in the product documentation. But yes, when you changed the router it has to be setup for external access.
I have a wireless security system, the Swann NVK-460 (incidentally, not a very good system) which has a built in router that connects to the cameras. However, to access the cameras on your phone or outside of the system you need internet access which is why I have to connected to my Asus router which is connected to my ISP, Rogers modem/router
When I was using my dual band Asus RT-N68U it worked fine. But I decided to upgrade to the tri-band Asus RT-AC3200. Since then I have been unable to connect to the internet. The cameras are still able to communicate to the Swann DVR/router but I cant access them through any outside line any more.
Do I need to enable some type of setting? or open a port?
Any help or suggestion would be appreciated.