I think I also have the same problem.
When I try to get in with Iphone / Android App ZSight I get the message "Your device is offline". The problem for me is that I also cannot access the NVR over WIFI. I have a PC on the same network as my ZP-NE14-S.
I installed the pc application ZViewer on this machine and when I search the LAN, I only find the four cameras, which are only connected over the NVR. I don’t understand why it is possible to find the cams without the NVR. All cameras could also be accessed over the ZViewer pc application. But the NVR is gone. When I try to ping the local IP of the NVR I get a positive result. But it is impossible to access it over the application.
What is happening with my NVR? In the first 2 months I never had such a problem. Now the NVR falls out fully every 24-48 hours. If I say the local staff to off and on again the device, it runs for this period.
I have to look when the system is restarted from the local staff.