BLE characteristic notification fires only once for iOS on sending multiple ones , works in android.

Am trying to send quite a huge amount of data (1000 to 2000 bytes) over ble .Using Aritchie bluetooth nuget for the same .https://github.com/aritchie/bluetoothle
Am sending it by creating multiple packets based on MTU and send them via notification. For android it works perfectly, get all the data but for iOS the notification event get's fired only once.
Is there something on iOS side that I need to take care of specifically or is this a known behaviour ?

below is the code snippet of notification

     InfoCharacterstic.RegisterAndNotify().Subscribe(notifyResult =>
                {
                        string notificationResponse = Encoding.ASCII.GetString(notifyResult.Data);
                        switch (ExternalDevice.GetInstance().State)
                        {......