Cannot add POE cameras to NVR

I bought a used NVR that appears to be in very good shape. It boots up and the firmware is updated to newest version and has V3 N2MB02 Hardware configuration. I also formatted the hard drive. I have set up a super admin account.

I previously (and currently) have three cameras set up on POE injector and can see all through the App with no issues. I then connected the cameras ethernet cables directly to the back of the NVR and they show up in the list to choose from when I check Add Camera. I enter the password and it attempts to log in and then says “connection failed”. I have tried doing reset on the cameras via the Poe injector and then plugging into the NVR and it still will not connect. Additionally, when cameras are connected back to the POE injector the NVR sees the cameras when I click add camera but again it will not connect to them. I made the password super simple to make sure it wasn’t a password problem.

The NVR shows up in the App but there are no cameras connected to it. I know the NVR is powering the cameras because the spot lights come on when it’s dark.

Anyone have any ideas?