Cameras going off line after a week?

[rosswill]

Hello I have started experiencing issues with all 7 cameras going off line after around a week. The fix for I have found for this has been to log into my NVR and perform a reboot remotely after which all cameras are back working again. Any idea what may be causing this? A failing NVR perhaps? As far as I can tell the network connections are all good. Each camera is connected directly to the NVR which is running V4.60.005. Thank you