For remote access, if you preview one channel, use the smooth mode to preview, the required network uplink bandwidth is calculated according to the upper limit of the bit rate of the device's sub-stream; if you preview one channel, use the HD mode to preview, the required network upstream bandwidth is based on the device's main stream Calculation of upper limit of code rate. 

View path for specific values of code stream: main menu-video configuration-encoding parameters, the upper limit value of the video parameter bit rate corresponds to the main stream; the upper limit of the sub stream parameter bit rate click on the sub stream to view.