Wired cameras go offline if internet connection allowed

An older friend of mine had an 8 channel NVR connected to their cameras via a repeater. Before the warranty expired, the wired cameras had all gone offline, so we had the repeater replaced under warranty, which resolved the issue.

Zmodo did have a repeater, so they sent us a 8 channel NVR without a drive to use in its place. Everything worked fine for a while (until some time after the warranty expired), and then all the cameras went offline again. As with the repeater, there was a “fast flash” on the LED activity indicator on each port a camera was plugged into.

I initially thought this was again a problem of the power supply to the cameras, but after bringing her NVR to my home and doing a lot of testing, I discovered everything worked fine as long as I don’t permit an internet connection.

Any ideas on what is going on?

I should note this only affects wired cameras. Her wireless cameras were still working fine. This topic is also an update to my earlier topic:
http://community.zmodo.com/t/power-supply-for-zmodo-wireless-cameras/10249