If you can connect your NVR for remote view through your laptop or pc but you cannot access live ip camera through Android apps then following configuration will help solve your issue.
Also you can connect through local LAN home ip but outside of house any WiFi or mobile data you cannot connect.
For model like Hikvision
Click
1) Configuration
2) Networking
3) Basic Settings
4) NAT
5) Check-in Enable UPnP
6) Save
problem solved.
Visit Link http://www.homeprix.com/index.php?option=com_content&view=article&id=80:ivms-4500-connection-failed&catid=29:technical&Itemid=165