Using theEthernet/Advanced Chat Server example adapted for Zephyr (seeattachment), the Telnet connection closes right after the greeting message.

Serial output shows:

Chat server address: 192.168.2.9We have a new client #0

Client side:

Connected to 192.168.2.9.Hello, client number: 0Connection closed by foreign host.

The connection drops immediately, before any data can be exchanged.