C# Telnet to Cisco routers

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C#

TcpClient

Cisco

I am trying to connect to a Cisco router via telnet but i don't need to log in only to get the banner (banner = information the router presents before you get into username & password input))

Banner Example:

*
Welcome To 101044555@xxxxxxx *
----------------------------- *
*
ADSL Line : xxxxx 5M *
*
Warning: *
Any unauthorized access to *
this system is unlawful, and *
may be subject to civil and/or *
criminal penalties! *
*
\ CONFIGURED BY-AY *
(o> *
//\ *
V/_ *
|| *
|| *
*

I need only the number before the "@"

The problem I can get any output at all. I am guessing it is because the session does not end naturally

namespace TelNetTesting
{ 
    class Program
    {
        static void Main(string[] args) 
        {
            Console.WriteLine("Please enter the name of a server:"); 
            string server = Console.ReadLine(); 
            TcpClient client = new TcpClient(server, 23); 
            StreamReader sr = new StreamReader(client.GetStream()); 
            StreamWriter sw = new StreamWriter(client.GetStream());
            
            try
            {
                sw.WriteLine("exit");
                sw.Flush();
    
                string data = sr.ReadLine();
                while (data != null)
                {
                    Console.WriteLine(data);
                    data = sr.ReadLine();
                }
                client.Close();
            }