A firmware update was recently released for the NVR6XX-4KS2 series devices.
Information, instructions, and download links can be found Here
From Dahua Wiki
There is no code stream when I log in and the network program restarts constantly after upgrade.
- Check if there is IP conflict or network disconnection.
- Check if the device is under normal power supply.
- Check if each connection line is loose inside the device after disassembling the camera.
- Check if the application program of IPC is corresponding to the model, and check if N/P format program is correct.
- Check if the control and WEB are correct, there is control running permission under WIN7, you can delete the control under C:\Program Files\webrec and eliminate IE buffer memory to reload control and WEB. Please run IE as administrator for WIN 7, you need to install QuickTime plug-in if it is non-IE browser.