@Soundchasrv
I think an android/ios app that is much better and intuitive than DMSS is Amcrest View Pro(AVP). It will work with an Amcrest or Dahua NVR. But Amcrest and Dahua have different P2P servers, so AVP with Dahua NVR would need to use a VPN as mentioned for BI.
AVP will work with a...