While the problem of the original poster's camera dropping out seems to be solved, I thought I would share a similar experience, with a different solution, that I had a few years ago.
I had several POE IP cameras (Hikvision) mounted externally on the house and connected up to a Hikvision NVR...
From reading a number of threads here, it appears that the important things to sort out when creating an effective LPR camera arrangement at night include:
1) Small camera angle
2) A larger lens size so the camera can provide a zoomed field of view (wide-angled lenses are a no no)
3)...