Hi @ShiLin1568 , try following this procedure: deactivate Wifi, go into your device settings and move the network from 4G to 2G (3G if it's an iPhone), wait for E to appear and turn off the device for a few minutes. Turn it back on, wait for the E to reappear and switch the network back to 4G. The switch and turning off (not restarting) the smartphone lead to the acquisition of a new priority on the cell and a consequent improvement in the quality of the network. I am available.