System.Data.SqlClient.SqlException (0x80131904): Connection Timeout Expired 예외 발생 시 "[Pre-Login] initialization=48; handshake=1944;" 값의 의미

SqlConnection sqlCon = ...;
sqlCon.Open();

System.Data.SqlClient.SqlException (0x80131904): Connection Timeout Expired. The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement. This could be because the pre-login handshake failed or the server was unable to respond back in time. The duration spent while attempting to connect to this server was - [Pre-Login] initialization=48; handshake=1944; ---> System.ComponentModel.Win32Exception (0x80004005): The wait operation timed out at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling)
at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()

연결 제한 시간이 만료되었습니다. 사전 로그인 핸드세이크 확인을 사용하려는 동안 제한 시간이 경과되었습니다. 이 문제는 사전 로그인 핸드세이크가 실패했거나 서버가 시간 내에 응답할 수 없기 때문일 수 있습니다. 이 서버에 연결하려고 시도할 때 걸린 시간은 [사전 로그인] 초기화=48, 핸드세이크=1944입니다. ---> System.ComponentModel.Win32Exception (0x80004005): 대기 작동이 시작 초과되었습니다. 

Password=...; User ID=...; Initial Catalog=...; Server=...; CONNECTION TIMEOUT=2;

using System;
using System.Net;
using System.Net.Sockets;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            TcpListener tl = new TcpListener(IPAddress.Any, 2222);
            tl.Start(); // 접속 대기만 할 뿐 연결을 Accept하지 않음.

            while (true)
            {
                Console.ReadLine();
            }

            tl.Stop();
        }
    }
}

Password=...; User ID=...; Initial Catalog=...; Server=tcp:localhost,2222; CONNECTION TIMEOUT=2;

Pooling = false;Password=...; User ID=...; Initial Catalog=...; Server=tcp:localhost,2222; CONNECTION TIMEOUT=2;