Can not perform ChatServer and ChatClient, help me!

No. There was no need to change these:

IPAddress gateway(192,168,1, 1);
IPAddress subnet(255, 255, 0, 0);

Unless you are trying to connect to the APNIC Debogon Project in Australia, you probably need to change:

// Enter the IP address of the server you're connecting to:
IPAddress server(1,1,1,1);