Cannot access past video from client

My NVR access is spotty from the desktop and iOS platforms. However, one of the cameras is connected via router and POE switch and can be accessed consistently. Additionally, while the coverage in the NVR is a complete record over the past ~2 weeks, I can only access a couple of hours from a couple of days from the client or app. Any ideas???

Hi Aic,

May I confirm more details and offer solution?
1. You connect the camera directly by desktop/ios platforms, it can be consistently connected in network.
2. You connect the camera to the NVR, and connect the NVR to the desktop/ios, the NVR can not be connected in network consistently.
3. You connect the camera to the NVR, and connect the NVR to the desktop/ios, the camera can not be connected on NVR consistently, but the NVR is connected well.

Would you please kindly confirm which points are correct? I will offer solution to you upon your confirmation. Thanks.