1) Whether the camera on the device is connected, whether there is a local image 2) Whether the client's network status is normal (the network speed is too slow, which will cause delay) 3) Whether to open the preview correctly (double-click the channel under the device) 4) The URL1 column in the server-side configuration file is not configured or the configuration is not the device-side reporting server-side address 5) Computer graphics card 3D acceleration is not turned on 6) Computer firewall intercepts video data 7) To check whether the video stream of the device and the client are encrypted, it needs a one-to-one correspondence (consult the manufacturer)