A network extender is a device that can effectively extend the network transmission distance. The principle is to modulate the network digital signal into an analog signal through telephone line, twisted pair, coaxial line for transmission, and then demodulate the analog signal into a network digital signal at the other end. The network extender can break through the limitation of the traditional Ethernet transmission distance within 100 meters, and can extend the network signal to 350 meters or even longer. It extends the limit of the network transmission distance from 100 meters to hundreds of meters or more, and can easily realize the interconnection between hubs, switches, servers, terminals and remote terminals.