Remoting对象错误:Unable to connect to the remote server

服务端有两个MBR类，TSystem、TDBSQLControl
TSystem以Singleton方式注册，其提供一个方法GetDBControl()给客户端提供TDBSQLControl类

客户端Activator.GetObject得到TSystem实例后，通过TSystem得到TDBSQLControl实例
现在的问题是这个实例无法访问，即使是.ToString()方法，都会出错


我实验了几种情况：
1：如果以我的开发电脑(XP系统)做服务器，那么一切都正常
2：如果以服务器（2003SERVER）做服务器，如果客户机是内网端口192.168.2.60，也一切都正常
3：如果以服务器（2003SERVER）做服务器，如果客户机是外网端口192.168.117.60，
那么出现错误：由于连接方在一段时间后没有正确答复或连接的主机没有反应，连接尝试失败
奇怪的是TSystem实例已经正常获得，并能正常操作。


服务器（2003SERVER）做服务器具有两个网址 192.168.2.61 和222.190.196.245

请教各位是什么问题？多谢

服务端代码
namespace nsBusiness
{
public class TSystem:MarshalByRefObject
{
public TSystem()
{
}
public virtual string Login(string aUserName,string aPassword)
{
string LoginID = aUserName + aPassword;
Console.WriteLine("User Login:{0};{1}");
return LoginID;
}
public nsDBControl.TDBSQLControl GetDBControl()
{
return new nsDBControl.TDBSQLControl();
}

}
}
namespace nsDBControl
{
public class TDBSQLControl : MarshalByRefObject
{
public TDBSQLControl()
{
}
public DataSet Query(string aSql, string str)
{
Console.WriteLine("Query" + aSql);
return null;
}
}
}

class Program
{
static void Main(string[] args)
{
nsBusiness.TSystem System = new nsBusiness.TSystem();
RemotingConfiguration.Configure("JSSCServerRemotingConfig.config", false);
PublicTDBSQLControl();
Console.ReadLine();
}
public static void PublicTDBSQLControl()
{
System.Type objType = typeof(nsBusiness.TSystem);
RemotingConfiguration.RegisterWellKnownServiceType(objType, "Mark1", WellKnownObjectMode.Singleton);

}
}

JSSCServerRemotingConfig.config文件内容：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<channels>
<channel port="9019" ref="tcp"/>
<channel port="9089" ref="http"/>
</channels>
</application>
<customErrors mode="Off"/>
</system.runtime.remoting>
</configuration>

客户端代码
nsBusiness.TSystem sys = (nsBusiness.TSystem)Activator.GetObject(typeof(nsBusiness.TSystem),
"http://222.190.196.245:8089/mark2");;
string loginid=sys.Login("aa", "bb");
nsDBControl.TDBSQLControl db = sys.GetDBControl();
db.Query("ccc","cbbb"); --出错，错误：由于连接方在一段时间后没有正确答复或连接的主机没有反应，连接尝试失败
MessageBox.Show("OK!");

详细错误信息：
Server stack trace:
at System.Net.HttpWebRequest.GetRequestStream()
at System.Runtime.Remoting.Channels.Http.HttpClientTransportSink.ProcessAndSend(IMessage msg, ITransportHeaders headers, Stream inputStream)
at System.Runtime.Remoting.Channels.Http.HttpClientTransportSink.ProcessMessage(IMessage msg, ITransportHeaders requestHeaders, Stream requestStream, ITransportHeaders& responseHeaders, Stream& responseStream)
at System.Runtime.Remoting.Channels.SoapClientFormatterSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at nsDBControl.TDBSQLControl.Query(String aSql, String str)
at TestConnect.Form1.button3_Click(Object sender, EventArgs e) in D:\DOTNET2005\TestConnect\TestConnect\Form1.cs:line 94