I also purchased 2 of the DCS-935L from Amazon and I'm experiencing the same issue (white screen intermittently during the day) with both units when they are facing outside, behind a window, facing a street. Both were replacing DCS-932L that have never had an issue in the same location (external window facing). I thought they were freezing up until I noticed I could access the Admin GUI, still hear audio, and if I leave them they will come back into focus during the night (which confirmed they were switching to Night mode)
I tried the following over the last 2 weeks:
-Resetting to Defaults, Changing Wireless 5.2 to 2.4 and channels, B/W mode, Firmware updates (1.07 with factory reset afterwards), and etc.
-Auto, Manual, and Day Mode Schedule will reproduce the white screen multiple times during the day. Mid morning, example 8-9AM, it occurs more frequently. When it was recently overcast, on a Sunny Day, it occurred about every hour during the day.
-Following up with Customer Support (to inform me they were defective).
Work Arounds
-Changing to Day Mode is the only way to prevent it from switching to Night Mode. Although this defeats the purpose as I need to switch it back manually if I want to record night footage with my DNR-202L.
-Moving the same cameras to an indoor facing location, not window facing, will switch between Day/Night correctly.
-Power cycling will return functionality.
-Only other method to restore is switch to Day Mode only before resetting within the ADMIN Page. If you don't, example leaving it in auto, a reset through the gui will not correct it.
I also agree this appears to be a bug with the sensor with sunlight or car reflections, but it's odd is the Day Mode Schedule will not prevent it (which would be a decent work around until it was corrected hopefully in firmware). In my experience the sensor will override this option.
I'm nearing the return window as well and will issue the return request today through Amazon. It's unfortunate as I'm a big fan of Dlink Cameras. I have probably purchased over 40 cameras in the last few years for myself or family (DCS-930, 932, 5010, 5009, 5029) but there is an issue with this model if you attempt to leverage it for outside purposes (example through a window).