A firmware update was recently released for the NVR6XX-4KS2 series devices.
Information, instructions, and download links can be found Here
From Dahua Wiki
After I connected to the IP channel, there one*window output is OK, but there is no multiple*window output.
There are following possibilities:
- Lower, FPS, Bitrate, change CBR to VBR and set to sub-stream on some of the cameras.
- Check the sub stream of the camera has been enabled or not.
- Check the sub stream type of the camera is H.264 or not.
- Check the device supports camera sub stream resolution or not (such as 960H, D1,CIF,etc.)