if the Cmsclient shows you a cry face when you want to watch the video feed, it means the RTSP password is incorrect or this function hasn't been enabled. To solve this, you have to login app and go to settings, find the menu NVR and Rtsp, then enable it and set a new password.
The next, you may right click the camera ID on the software and select property and modify its password, and fill your newly created RTSP password.
