PC can’t see the Cameras

[AlanPham]

Hello you all please help
I have 2 Bi system 2 locations
A: 12 cameras ( 8 Armcrest 4 Reolink)
B:16 cameras All Amcrest
2 weeks ago A lost all signals and when I try to install it again the PC can’t find the ip address
But I can still see the cameras using the Amcrest& Reolink app in my phone
This week system B lost 6 cam same problem and I retired everything in my PC firewalls disabled too ! Please help

 

[TonyR]

Insure a recent Windows update did not change the properties of the BI server's Ethernet interface from "private" to "public".

Is it safe to assume that both BI servers and all IP cameras have been assigned unique static IP addresses?