Joogers

Hello, I have 4 Hikvision cameras hooked up to a Hikvision NVR DS-7616NI-SE/P PoE. This system has been running fine for over 12 months. Lately one camera (a Hikvision IP camera DS-2CD2732F-IS) keeps dropping off my system and showing an error code of "416" when I try and access it. If I reboot the system the camera starts working again but drops off over a period of time. Anyone have any ideas how to fix this. Cheers