Not sure I fully understand the problem, but as
@sebastiantombs mentioned, if you can hit the web GUI then the camera would appear to be working.
The NVR showing a red indicator typically means it sees the camera, but can’t communicate with it due to not having the right credentials.
If it’s a brand new camera, plugging in the camera the first time out of the box automatically assumes the same credentials as the NVR. You would see a green indicator on the NVR registration page and using the blue IE icon,
login to the camera web GUI.
If the login/pass has been changed on the camera to something other than that of the NVR, you would need to click the “edit” icon on the NVR registration page (pencil icon) and enter the camera login/pass information there so that the NVR knows how to login to the camera and communicate with it. Hit refresh, wait a few minutes, and it should turn green and the IE icon light up to allow logging into the camera from the registration page.