Do not broadcast in 3G + info message

res/layout/activity_device.xml

@@ -70,7 +70,7 @@
     </LinearLayout>
 
     <TextView
-        android:id="@+id/unpair_message"
+        android:id="@+id/not_reachable_message"
         android:visibility="gone"
         android:layout_width="match_parent"
         android:drawableStart="@drawable/ic_error_outline_black_48dp"
@@ -82,6 +82,19 @@
         android:textAppearance="?android:attr/textAppearanceMedium"
         />
 
+    <TextView
+        android:id="@+id/on_data_message"
+        android:visibility="gone"
+        android:layout_width="match_parent"
+        android:drawableStart="@drawable/ic_error_outline_black_48dp"
+        android:drawableLeft="@drawable/ic_error_outline_black_48dp"
+        android:drawablePadding="8dip"
+        android:layout_height="match_parent"
+        android:gravity="center_vertical"
+        android:text="@string/on_data_message"
+        android:textAppearance="?android:attr/textAppearanceMedium"
+        />
+
     <ListView
         android:id="@+id/buttons_list"
         android:layout_width="match_parent"

res/values/strings.xml

@@ -193,6 +193,7 @@
     <string name="device_rename_confirm">Rename</string>
     <string name="refresh">Refresh</string>
     <string name="unreachable_description">This paired device is not reachable. Make sure it is connected to your same network.</string>
+    <string name="on_data_message">It looks like you are on a mobile data connection. KDE Connect only works on local networks.</string>
     <string name="no_file_browser">There are no file browsers installed.</string>
     <string name="pref_plugin_telepathy">Send SMS</string>
     <string name="pref_plugin_telepathy_desc">Send text messages from your desktop</string>

src/org/kde/kdeconnect/Backends/LanBackend/LanLinkProvider.java

@@ -31,6 +31,7 @@ import org.kde.kdeconnect.Backends.BaseLinkProvider;
 import org.kde.kdeconnect.BackgroundService;
 import org.kde.kdeconnect.Device;
 import org.kde.kdeconnect.Helpers.DeviceHelper;
+import org.kde.kdeconnect.Helpers.NetworkHelper;
 import org.kde.kdeconnect.Helpers.SecurityHelpers.SslHelper;
 import org.kde.kdeconnect.Helpers.StringsHelper;
 import org.kde.kdeconnect.NetworkPackage;
@@ -362,6 +363,11 @@ public class LanLinkProvider extends BaseLinkProvider implements LanLink.LinkDis
 
     private void broadcastUdpPackage() {
 
+        if (NetworkHelper.isOnMobileNetwork(context)) {
+            Log.w("LanLinkProvider", "On 3G network, not sending broadcast.");
+            return;
+        }
+
         new Thread(new Runnable() {
             @Override
             public void run() {

src/org/kde/kdeconnect/BackgroundService.java

@@ -119,7 +119,7 @@ public class BackgroundService extends Service {
         }
     };
 
-    private void onDeviceListChanged() {
+    public void onDeviceListChanged() {
         for(DeviceListChangedCallback callback : deviceListChangedCallbacks.values()) {
             callback.onDeviceListChanged();
         }

src/org/kde/kdeconnect/Helpers/NetworkHelper.java

@@ -0,0 +1,16 @@
+package org.kde.kdeconnect.Helpers;
+
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+import android.util.Log;
+
+public class NetworkHelper {
+
+    public static boolean isOnMobileNetwork(Context context) {
+        final ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+        NetworkInfo info = connMgr.getActiveNetworkInfo();
+        return (info != null && info.getType() == ConnectivityManager.TYPE_MOBILE);
+    }
+
+}

src/org/kde/kdeconnect/KdeConnectBroadcastReceiver.java

@@ -67,6 +67,7 @@ public class KdeConnectBroadcastReceiver extends BroadcastReceiver
                 BackgroundService.RunCommand(context, new BackgroundService.InstanceCallback() {
                     @Override
                     public void onServiceStart(BackgroundService service) {
+                        service.onDeviceListChanged();
                         service.onNetworkChange();
                     }
                 });

src/org/kde/kdeconnect/UserInterface/DeviceFragment.java

@@ -40,6 +40,7 @@ import android.widget.TextView;
 
 import org.kde.kdeconnect.BackgroundService;
 import org.kde.kdeconnect.Device;
+import org.kde.kdeconnect.Helpers.NetworkHelper;
 import org.kde.kdeconnect.Helpers.SecurityHelpers.SslHelper;
 import org.kde.kdeconnect.Plugins.Plugin;
 import org.kde.kdeconnect.UserInterface.List.CustomItem;
@@ -333,9 +334,11 @@ public class DeviceFragment extends Fragment {
 
                     boolean paired = device.isPaired();
                     boolean reachable = device.isReachable();
+                    boolean onData = NetworkHelper.isOnMobileNetwork(getContext());
 
                     rootView.findViewById(R.id.pairing_buttons).setVisibility(paired ? View.GONE : View.VISIBLE);
-                    rootView.findViewById(R.id.unpair_message).setVisibility((paired && !reachable) ? View.VISIBLE : View.GONE);
+                    rootView.findViewById(R.id.not_reachable_message).setVisibility((paired && !reachable && !onData) ? View.VISIBLE : View.GONE);
+                    rootView.findViewById(R.id.on_data_message).setVisibility((paired && !reachable && onData) ? View.VISIBLE : View.GONE);
 
                     try {
                         ArrayList<ListAdapter.Item> items = new ArrayList<>();

src/org/kde/kdeconnect/UserInterface/PairingFragment.java

@@ -36,6 +36,7 @@ import android.widget.TextView;
 
 import org.kde.kdeconnect.BackgroundService;
 import org.kde.kdeconnect.Device;
+import org.kde.kdeconnect.Helpers.NetworkHelper;
 import org.kde.kdeconnect.UserInterface.List.ListAdapter;
 import org.kde.kdeconnect.UserInterface.List.PairingDeviceItem;
 import org.kde.kdeconnect.UserInterface.List.SectionItem;
@@ -60,6 +61,8 @@ public class PairingFragment extends Fragment implements PairingDeviceItem.Callb
 
     boolean listRefreshCalledThisFrame = false;
 
+    TextView headerText;
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
@@ -74,10 +77,10 @@ public class PairingFragment extends Fragment implements PairingDeviceItem.Callb
 
         rootView = inflater.inflate(R.layout.activity_list, container, false);
 
-        TextView text = new TextView(inflater.getContext());
-        text.setText(getString(R.string.pairing_description));
-        text.setPadding(0, (int) (16 * getResources().getDisplayMetrics().density), 0, (int) (12 * getResources().getDisplayMetrics().density));
-        ((ListView) rootView).addHeaderView(text);
+        headerText = new TextView(inflater.getContext());
+        headerText.setText(getString(R.string.pairing_description));
+        headerText.setPadding(0, (int) (16 * getResources().getDisplayMetrics().density), 0, (int) (12 * getResources().getDisplayMetrics().density));
+        ((ListView) rootView).addHeaderView(headerText);
 
         return rootView;
     }
@@ -104,6 +107,8 @@ public class PairingFragment extends Fragment implements PairingDeviceItem.Callb
                         }
                         listRefreshCalledThisFrame = true;
 
+                        headerText.setText(getString(NetworkHelper.isOnMobileNetwork(getContext()) ? R.string.on_data_message : R.string.pairing_description));
+
                         try {
                             Collection<Device> devices = service.getDevices().values();
                             final ArrayList<ListAdapter.Item> items = new ArrayList<>();