Try a reboot of the NVR.
And if they don't show after that, confirm that the IP address of the NVR is the same subnet of the cameras, which I would think they would be if the NVR found them.
Yes you could factory reset the cameras from the camera GUI - open up a browser (preferably IE or Edge with IE tab) and type in the IP address of a camera and the login screen will pop up.
But before you do that, delete all the cameras from the NVR and add cameras back one at a time. Do not move to the next camera until the camera shows up.
And if they don't show after that, confirm that the IP address of the NVR is the same subnet of the cameras, which I would think they would be if the NVR found them.
Yes you could factory reset the cameras from the camera GUI - open up a browser (preferably IE or Edge with IE tab) and type in the IP address of a camera and the login screen will pop up.
But before you do that, delete all the cameras from the NVR and add cameras back one at a time. Do not move to the next camera until the camera shows up.