이 오류 때문에 머리 다 빠지겠어요.. 고수님들 도와주세요.

- 개요
서버의 DB 데이터를 사용하는 클라이언트들의 DB 연결장애

- 서버 환경
운영체제 : Windows Server 2008
DB : MS-SQL 2008 Standard(SP2)

- 증상
DB와 통신 시 (Connect, SP 수정, Select 등등) 연결이 지연되거나 실패
통신 재 시도하면 연결 성공
(1. 3 ~ 5초정도 원활하게 연결되다가
2. 15 ~ 20초정도 연결장애..
3. 1번과 2번 무한반복)
DB 통신을 제외한 다른 연결은 이상증세 없음.

- 오류 메시지
제한 시간이 만료되었습니다. 작업을 완료하기 전에 제한 시간이 경과되었거나 서버가 응답하지 않았습니다. (Microsoft SQL Server, 오류: -2)

- 상세

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프로그램 위치:

   위치: System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   위치: System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   위치: System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
   위치: System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync()
   위치: System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket()
   위치: System.Data.SqlClient.TdsParser.ConsumePreLoginHandshake(Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean& marsCapable)
   위치: System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover)
   위치: System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
   위치: System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
   위치: System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
   위치: System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)
   위치: System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   위치: System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup, DbConnectionOptions userOptions)
   위치: System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   위치: System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   위치: System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   위치: System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   위치: System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   위치: System.Data.SqlClient.SqlConnection.Open()
   위치: Microsoft.SqlServer.Management.SqlStudio.Explorer.ObjectExplorerService.ValidateConnection(UIConnectionInfo ci, IServerType server)
   위치: Microsoft.SqlServer.Management.UI.ConnectionDlg.Connector.ConnectionThreadUser()

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- 조치내용
서버 방화벽에 1433 포트 허용 등록(인바운드, 아웃바운드)
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SQL 2008 서비스팩2 설치

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