Yes! WiFi RS21 can work with the current 4.2 firmware

I’ll put the full solution on Codeshare later but for now I thought I would post the base code I used to connect to my Android Galaxy Tab 2 Tablet using a WiFi connection.
I do not own (Or even want) a cell phone, so I have no idea if the code will work with one.

Not much error checking for now because the current code is only for testing if messages can be sent and received. As a note: I have used Bluetooth and the WiFi seems faster but we’ll see…

using System;
using System.IO;
using System.Collections;
using System.Threading;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Diagnostics;

using Microsoft.SPOT;
using Microsoft.SPOT.Presentation;
using Microsoft.SPOT.Presentation.Controls;
using Microsoft.SPOT.Presentation.Media;

using Socket = System.Net.Sockets.Socket;

using GHI.Premium.Net;
using Gadgeteer.Networking;
using GT = Gadgeteer;
using GTM = Gadgeteer.Modules;
using Gadgeteer.Modules.GHIElectronics;


//Using GHI .NET Micro Framework 4.2

// I guess I'm a client when connecting to my Android Galaxy Tab 2 Tablet

namespace AndroidWifiSpider
    public partial class Program
        //Your choice...
        //static bool useDebug = true;
        bool useDebug = false;
        bool useOnce = true; //Allow button to connect to TCP only one time

        Font MyFont = Resources.GetFont(Resources.FontResources.NinaB);

        string ssid = "xxxxxxxxxx";     // <<<<< You need to enter your SSID here
        string PassKey = "xxxxxxxx";    // <<<<< You need to enter your Password/Key here

        //This is my Android Tablet
        int port = 8080;                // <<<<< Enter port to use here
        string ip = "";      // <<<<< Enter IP to use here

        System.Threading.Timer Readtimer;
        //Short text messages used. We are not reading/writing files
        const int buffsize = 128; //Size for your needs

        byte[] readbuff = new byte[buffsize];
        byte[] data;

        Socket AndroidSocket;
        IPEndPoint ipep;

        Thread ReceiveDataThread; //Not using for now

        // This method is run when the mainboard is powered up or reset.   
        void ProgramStarted()
            multicolorLed.GreenBlueSwapped = true; //If needed - I need it

            //Begin StartWIFI() only after pressing the Startbutton
            Startbutton.ButtonPressed += new GTM.GHIElectronics.Button.ButtonEventHandler(Startbutton_ButtonPressed);

            display_T35.SimpleGraphics.AutoRedraw = true;
            display_T35.SimpleGraphics.BackgroundColor = GT.Color.LightGray;
            display_T35.SimpleGraphics.DisplayText("Press start button to begin WiFi", MyFont, Colors.Black, 5, 3);            
        //Allow access for deploy/debug if this application hangs in a endless loop.
        //If app hangs you can reset the main board and then deploy/debug
        private void Startbutton_ButtonPressed(Button sender, Button.ButtonState state)
            //Allow button press only one time
            if (useOnce) //If true
                useOnce = false;
                display_T35.SimpleGraphics.DisplayText("Starting WiFi - Using: " + ip +
                    " Port " +  port.ToString(), MyFont, Colors.Red, 3, 10);

                //WiFi begin
                //If not the first button press

        // Your router SSID and PassKey need to be set for this method

        void StartWIFI()

            if (!wifi_RS21.Interface.NetworkInterface.IsDhcpEnabled)
            wifi_RS21.Interface.WirelessConnectivityChanged += 
                new WiFiRS9110.WirelessConnectivityChangedEventHandler(Interface_WirelessConnectivityChanged);
            wifi_RS21.Interface.NetworkAddressChanged += 
                new WiFiRS9110.NetworkAddressChangedEventHandler(Interface_NetworkAddressChanged);

                WiFiNetworkInfo[] ScanResp = wifi_RS21.Interface.Scan(ssid);
                //Use to Scan for all SSID's
                //WiFiNetworkInfo[] ScanResp = wifi_RS21.Interface.Scan( ); 

                if (ScanResp != null && ScanResp.Length > 0)
                    //Your passkey needed here
                    wifi_RS21.Interface.Join(ScanResp[0], PassKey);
                    if (useDebug) { Debug.Print("Connected to Wireless network - " + ssid); }
                    if (useDebug) { Debug.Print("Failed to connect to Wireless network - " + ssid); }
            catch (Exception e)
                Debug.Print("!!Exception : " + e.Message);

            ipep = new IPEndPoint(IPAddress.Parse(ip), port);
            AndroidSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //Exception on Connect(ipep) if a delay is not used?
            //Exception using 1000, 2000,
            //3000 seemed to work without an exception,, So I'll use 4000 ;>)

            //Inform user that connection was successful
            //Send a greeting message to the Android device
            data = Encoding.UTF8.GetBytes("Hello from the Fez Spider.");

            //Send greeting to the Android Tablet

            //ReceiveDataThread = new Thread(ReceiveData);

            Readtimer = new Timer(new TimerCallback(ReceiveData), null, 100, 500);


        //This method needs a test of some kind to see if the socket is still available......
        public void ReceiveData(object obj)
            byte[] readbuff = new byte[buffsize];

            char[] chars = new System.Text.UTF8Encoding().GetChars(readbuff);
            string dataReceived = String.Empty;
            for (int i = 0; i < chars.Length; i++)
                dataReceived += chars[i];

            display_T35.SimpleGraphics.DisplayText(dataReceived, MyFont, Colors.Black, 2, 3);
            if (useDebug) { Debug.Print(dataReceived); }
            //Test - Echo received text back to the Android
            byte[] echo = new byte[buffsize];
            echo = Encoding.UTF8.GetBytes("Echo: " + dataReceived);

            //SocketException ErrorCode WSAESHUTDOWN 10058 Cannot send after socket shutdown.
            //Send bytes to Android
            AndroidSocket.SendTo(echo, ipep);
        void Interface_WirelessConnectivityChanged(object sender, WiFiRS9110.WirelessConnectivityEventArgs e)
            //Your code here   

        void Interface_NetworkAddressChanged(object sender, EventArgs e)
            //Your code here

    } //end class
} //end namespace

ADDED COMMENT: Does anyone know why the long delay is needed brfore AndroidSocket.Connect(ipep); ???

Everyone have a GREAT DAY!!