Connect to LAN and internet at same time?

Question

Simply put, I want to use my Android device to connect to a LAN but not lose my internet capabilities.

I have dug through Google's guides on network connections, but the only possible solution I have found is Wi-Fi Direct. Unfortunately, I don't think this is possible because the LAN does not support the Wi-Fi Direct protocol.

Is there a way to a connect to a Wi-Fi access point with no internet and remain connected to either cellular or a previous Wi-Fi access point which has internet?

Re-configuring the LAN is something I can do, if that helps

Edit: I have seen this question, but it does not look like there is an answer and it was asked over 3 years ago

Answer 1

You need to build a HttpClient that knows to only use the WiFi.

Android will check internet connections to see if it can get onto the internet with them and ignore them if it can't. Even for local IP addresses, which can be a pain.

This is part of a Dagger module I wrote to create a correctly configured OkHttp client.

/**
 * Find the WiFi Network object. If the WiFi is off this will return null. You might want to listen to the broadcasts from the WiFi system to retry when the WiFi is turned on.
 */
@Provides
public Network provideNetwork(ConnectivityManager connectivityManager) {
    for (final Network network : connectivityManager.getAllNetworks()) {
        final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
        final int networkType = networkInfo.getType();

        if (networkType == ConnectivityManager.TYPE_WIFI) {
            return network;
        }
    }

    return null;
}


/**
 * Create a HttpClient that will only use the network supplied. Changing this for the built in Apache HttpClient should be easy enough. 
 */
@Provides
public OkHttpClient provideOkHttpClient(final Network network) {
    if (network != null) {
        final OkHttpClient httpClient = new OkHttpClient();
        httpClient.setSocketFactory(network.getSocketFactory());

        Internal.instance.setNetwork(httpClient, new com.squareup.okhttp.internal.Network() {
            @Override
            public InetAddress[] resolveInetAddresses(String host) throws UnknownHostException {
                return network.getAllByName(host);
            }
        });

        return httpClient;
    }

    return null;
}