Planet Networking & Communication HDVR-430 User Manual page 64

When the current resolution is over the max resolution that the channel
supports, then a red "X" will be shown on the preview image. For example,
in full digital channel mode, the maximum resolution of channel is 720p. If
the HDVR connects to a camera with resolution over 720p (such as 1080p),
you will see the picture shown below.
Channel Type:
Hybrid Digital Video Recorder
64
HDVR series