I've had that a couple of times with these cameras, and each time it was fixed by replacing older, cheaper cat5e with better solid copper cable, and making sure they had their full power requirement from the switch/injector.
I'm using 2mtrs of shielded cat 6 ! Direct to the rear of the NVR, While testing.
Also using a both POE ( / ether or ) and high power 12v Psu, all with the same results.
I'm not going to actually mount this camera up, until I can iron out some of the problems with testing.
This camera has great potential, but as it stands at the moment, it's close, but no cigar.....
Tiny