TIdCMDTCPServer

I have this problem: on a wirelees network when my notebook go in stanby
mode the TIdCMDTCPServer is never informed and it take the connection of the
notebook active. When I reopen my notebook there is an error that it tell me
that there no connection.
I try to resolve this problem in this way:
on the client side I put a timer that every 1 minute it send a command to
the server;
on the server side  when the command arrive, it sets the hour of the arrive
to a field of type TDateTime to my User. I timer every 30 second check if
the delay of the last command sended by every user is great of 30 second. If
so it must delete the connession.
The proble is that I don't know how to do this. I prouve with
TIDContext.Removefromlist method that it doesn't work. The last version of
my prove is the above code:

procedure TMainForm.Check;
Var
  AList, AServerList: TList;
  AUser: TConnectedUser;
  AllOk: Boolean;
  I: Integer;
  TimeToCheck, ResultTime: TDateTime;
  ASecond: Word;
  function GiveSeconds(const Value: String): Word;
  Var
    AMinutesStr, ASecondsStr: String;
  begin
    AMinutesStr := Value[1];
    AMinutesStr := AMinutesStr + Value[2];
    ASecondsStr := Value[4];
    ASecondsStr := ASecondsStr + Value[5];
    Result := StrToInt(AMinutesStr) * 60;
    Result := Result + StrToInt(ASecondsStr);
  end;
begin
  TimeToCheck := now;
  AServerList := ServerTango.Contexts.LockList;
  try
   if AServerList.Count > 0 then
     begin
     AList := UserList.LockList;
      try
     AllOk := False;
     while not AllOk do
       begin
       for I := 0 to AServerList.Count - 1 do
         begin
         ResultTime := TimeToCheck -
TConnectedUser(AList[I]).BroadCastMessage;
            ASecond := GiveSeconds(FormatDateTime('nn:ss', ResultTime));
         AllOk := True;
         if ASecond > BroadCastInterval then
           begin
           AllOk := False;
           AUser := AList[I];
           AList.Delete(I);
           AUser.Free;
            AServerList.Delete(I);
            if AServerList.Count = 0 then
              AllOk := True;
           Break;
           end;
         end;
         end;
      finally
        UserList.UnlockList;
    end;
      end;
  finally
    ServerTango.Contexts.UnlockList;
  end;
end;

it function but when I try to end the server it doesn't.
How can I do this thing?
Perhaps I can intecept when the notebook enter in standby mode and
automatically disconnect from the server. It' s possible to do this and how?