SSL Connection Error While making a connection

I am totally new on this and after some research, trying to make a SSL/TLS connection with server to allow SOAP call outside defined network. I am using OKHttp3 library to make the call and sharing a .P12 file with private key and setting a SSL Socket Factory as shown below

setupKeyCert(context);    
 final OkHttpClient client = new OkHttpClient();
    client.newBuilder()
            .connectTimeout(30, TimeUnit.SECONDS)
            .sslSocketFactory(sslContext.getSocketFactory(), mainX509TrustManager);

and setting keystone and Trust Manager in

setupKeyCert()

as

try {
            KeyStore keyStore = KeyStore.getInstance("PKCS12");
            KeyManagerFactory keyManagerFactory = null;
            if(buildEnvironment == "prod")
            {
                keyStore.load(context.getAssets().open(Constants.CERT_PROD_FILE), password);

                keyManagerFactory = KeyManagerFactory.getInstance("X509");
                keyManagerFactory.init(keyStore, Constants.CERT_PROD_VALUE.toCharArray());

            } else
            {
                keyStore.load(context.getAssets().open(Constants.CERT_FILE), Constants.CERT_VALUE.toCharArray());
                keyManagerFactory = KeyManagerFactory.getInstance("X509");
                keyManagerFactory.init(keyStore, Constants.CERT_VALUE.toCharArray());
            }
            KeyManager[] keyManagers = keyManagerFactory.getKeyManagers();

            //Adding TrustManagerFactory
            TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
            trustManagerFactory.init(keyStore);
            TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
            if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
                throw new IllegalStateException("Unexpected default trust managers:"
                        + Arrays.toString(trustManagers));
            }
            mainX509TrustManager = (X509TrustManager) trustManagers[0];


            sslContext = SSLContext.getInstance("TLSv1.2");
            sslContext.init(keyManagers, null, null);
        } catch (FileNotFoundException f)
        {
            Log.e("Excption File", String.valueOf(f));
        } catch (Exception i)
        {
            Log.e(TAG, "Exception", i);
        }

Where Constant.CERT_PROD_FILE refers to constant string which contain file name. When debugging or making call, I am getting below error

javax.net.ssl.SSLProtocolException: SSL handshake terminated: ssl=0x8a163cc0: Failure in SSL library, usually a protocol error error:10000410:SSL routines:OPENSSL_internal:SSLV3_ALERT_HANDSHAKE_FAILURE (external/boringssl/src/ssl/s3_pkt.c:610 0x9f7e3d00:0x00000001)

I am not sure what am I missing and I have tried different solution including bug related to android 7 issue but it's still not working. I tried to debug and can only see the above error, so not sure if the issue is with server or client. Thanks for help in advance.