OkHttpClient with Mobile Carrier issue

My Application API perform weird behavior. One of my live app's api expected response time 2 to 3 seconds but it takes long time to response!

Test Cases:

1. Works with WIFI = Yes
2. Works with Airtel carrier = Yes
3. Works with Jio carrier = Yes
4. Works in Other countries network =Yes
5. Works in mobile browser with Vodafone Idea carrier = Yes
6. Works with Same API with IOS app using Vodafone Idea carrier = Yes

Main Issue: Issue with Vodafone Idea carrier using App = Very Slow

Case1.

 URL url = new URL("https://example.com");
                urlConnection = (HttpsURLConnection) url.openConnection();
                urlConnection.setReadTimeout(10000);
                urlConnection.setConnectTimeout(10000);
                int code = urlConnection.getResponseCode();
                if (code !=  200) {
                    throw new IOException("Invalid response from server: " + code);
                }

                BufferedReader rd = new BufferedReader(new InputStreamReader(
                        urlConnection.getInputStream()));
                String line;
                while ((line = rd.readLine()) != null) {
                    Log.e("data", line);
                }

Outcome:

• First time 40 to 50 seconds.
• On every next consecutive call it will return within 2 to 5 seconds as per expectation.

Case 2:

OkHttpClient okHttpClient = new OkHttpClient.Builder().build();

        Request.Builder requestBuilder = new Request.Builder()
                .url("https://example.com")
                .addHeader("Content-Type", "application/json");
        Request request = requestBuilder.build();
        Log.e("APi", "REQUEST: "+request.toString());

        Call call1 = okHttpClient.newCall(request);
        call1.enqueue(new Callback() {
            @Override
            public void onFailure(@NotNull Call call, @NotNull IOException e) {
                Log.e("APi", "APi Failed");
            }

            @Override
            public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException {
                Log.e("APi", "APi isSuccessful:" + response.isSuccessful());
                Log.e("APi", "Response:" + response.body().string());
            }
        });

Outcome:

• Every time takes 40 to 50 seconds.

Case 3:

    OkHttpClient okHttpClient = new OkHttpClient.Builder()
.connectTimeout(1, TimeUnit.SECONDS).build();
    
            Request.Builder requestBuilder = new Request.Builder()
                    .url("https://example.com")
                    .addHeader("Content-Type", "application/json");
            Request request = requestBuilder.build();
            Log.e("APi", "REQUEST: "+request.toString());
    
            Call call1 = okHttpClient.newCall(request);
            call1.enqueue(new Callback() {
                @Override
                public void onFailure(@NotNull Call call, @NotNull IOException e) {
                    Log.e("APi", "APi Failed");
                }
    
                @Override
                public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException {
                    Log.e("APi", "APi isSuccessful:" + response.isSuccessful());
                    Log.e("APi", "Response:" + response.body().string());
                }
            });

Outcome:

• Every time it takes 5 to 6 seconds.

Note: I am afraid to use .connectTimeout(1, TimeUnit.SECONDS) as 1 second in app It started to give more api failure and not looks correct solution as well.

Update CaseStudy:

failed to connect to xxx.com/2001:4860:4802:36::15 (port XXX) from /2402:3a80:1b8f:ca21:847:21a8:5ffc:fc30 (port XXX) after 10000ms  

package okhttp3.internal.connection.RealConnection class. trying to establish connectSocket but getting error.

-> After adding "www" www.example.com into my domain. Response time change from 40 seconds to 12 seconds approx for okhttp library.