I had a eight year-old
"I had a eight year-old system and cameras and ethernet cables worked fine. Eventually, the NVR just died. They did not make a new NVR that was compatible with my old cameras so I bought an entire new system. And two of the new cameras frequently go off-line for no reason. I have to unplug them and plug them back in again. Never once did this happen with the old system for eight years. If you're traveling or not at home when the system goes off-line, then there's nothing you could do until you get home."