Nothing in BI can do it so you can eliminate that. Maybe on the BI server or elsewhere on your network if, for example, you had an IP conflict or multiple DHCP servers running. But that doesn't answer why the cam would go from static to DHCP. Not sure what happens on that cam if there's some IP conflict? Maybe fail to DHCP?Any BI or NVR experts that might know of a hidden setting somewhere I'm missing? Currently we use the web GUI to get into the NVR, maybe it's a setting that I have to get to via console?
Some camera config setting in the NVR seems like a good place to start looking. Don't know the Dahua NVRs to suggest where.
Are you setting the static IP in the cam itself or through the NVR?