After I connected to the IP channel, there multiple\*window output is OK, but there is no one\*window output.

There are following possibilities:

Check there is video from the IP channel or not. Please go to the main menu>info*>System*>BPS to view bit stream real*time information.
Check the main stream of the camera has been enabled or not.
Check the main stream type of the camera is H.264 or not.
Check the device supports camera main stream resolution or not (such as 960H, D1, HD1 and etc.).
Check camera network transmission has reached the threshold or not. Please check the online user of the camera.
Was this article helpful?
Thank you!