A firmware update was recently released for the NVR6XX-4KS2 series devices.
Information, instructions, and download links can be found Here
From Dahua Wiki
Cross stripe or diagonal stripe appears in the image of IPC.
- Bad connection for the video cable. Check or test with a different cable, connection and port.
- Strong current interference. Check if there are other devices causing this issue. It could be the cable too close to another device. Mounting the camera on a metal surface can cause current interference from bleeding electrical currents.
- A ground loop can be causing the stripes. Ground loops occur for a few different reasons but this issue will always present itself in the form of horizontal lines running across your screen (hum bars).Faulty power supplies and/or faulty cable are frequent culprits but improper wiring in the home/building is much more common. If you discover that your image problems are related to the power supply or cable, you simply need to swap them out. However, if bad wiring in the structure is found to be the problem, locating it and then having someone fix it is not exactly a quick or cheap fix. This is where ground loop isolators come in. They’re simple plug-and-play adapters that attach to the back of your camera and then filter this electrical noise out of your video feed.
- Power Supply.There are several things that can go wrong with a power supply but related problems will always appear in your video as “rolling lines.” These are horizontal lines across your screen that will normally move from bottom to top; lines moving in the opposite are not unheard of so don’t rule it out. The image from your camera will remain behind these lines and will not move with them. This can often be confused with the lines you can get from a ground loop problem, but the lines caused by a group loop will remain in a single static position.