A firmware update was recently released for the NVR6XX-4KS2 series devices.
Information, instructions, and download links can be found Here
From Dahua Wiki
IR effect is bad.
- Failed to enable all IR lights. Make sure the specified power supply is used for the correct voltage. Using the unspecified power supply can result in damaging the IR lights in addition to the camera.
- IR not illuminating far object. There are limitations of how far the IR can reach. Please refer to the specifications of the camera.
- IR-CUT is set as color mode, which caused the front-end sensor to fail to sense IR light. Set Camera IR setting to auto, this setting should have the front-end sensor to detect the IR.
- IR picture is white. It is very possible it is reflecting off a surface. Glass and reflective surfaces will cause the IR to reflect off of it. Change the elevation and angle. When you use the device on the table (especially rough surface), the IR light will shoot back to the lens, which will cause bad IR effect and white picture. At this moment, you should adjust the elevation angle of the lens or place the device on the edge.
- Check if camera IR is set to auto. If it is set to manual, the IR will not illuminate when it is dark.
- IR is not illuminating powerful enough. Make sure the plastic is off the cameras lens. The plastic can affect the effectiveness of the IR.
- IR is glaring. Check if there are debris on the cameras glass. Debris can cause infrared glare.