Are you unable to access all of the cameras? One of the common CCTV camera issues is an inability to view all of the cameras. With IP CCTV, cameras must be connected to a local area network (LAN).
If you are unable to access all of your CCTV cameras and you know that they are powered up and working, then the problem could be an IP address conflict.
Each CCTV camera needs to be configured with a unique IP address. For cyber security reasons and to avoid CCTV IP addresses interference, It is advisable to have all your IP CCTV in their own VLAN and configured with static IP addresses.