java.net.ProtocolException: unexpected end of streamのエラーが出ます

##android初心者です。
##jsonでサーバーと通信する処理を作成しました。正常に稼動はするのですが１時間以上経過した際にjava.net.ProtocolException: unexpected end of streamのエラーが出て終了します。
##まだ実機では試していません。エミュレータ上の現象となります。
##エラー内容で検索すると以下の文を追加するとあるのですがどこの箇所に入れるのか分かりません。

java
1okHttpClient = new OkHttpClient.Builder()
2            .addNetworkInterceptor(new Interceptor() {
3                @Override
4                public Response intercept(Chain chain) throws IOException {
5                    Request request = chain.request().newBuilder().addHeader("Connection", "close").build();
6                    return chain.proceed(request);
7                }
8            })
9            .build();

java
1 public String getGET(){
2
3
4        final String story_id = "";
5        try
6        {
7            // APIを飛ばす処理
8            new AsyncTask<Void, Void, String>() {
9
10                @Override
11                protected String doInBackground(Void... params) {
12                    String i_story_id = "";
13                    String email = "*******@******.co.jp";
14                    String password = "**********";
15
16                    String sendData = String.format("{ \"email\":\"%s\", \"password\":\"%s\" }",email, password);
17
18                    try {
19                        byte[] sendJson = sendData.getBytes("UTF-8");
20                        URL url = new URL("http://192.168.33.10/theater/Mainmenu/read/");
21                        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
22
23                        // 接続するための設定
24                        connection.setRequestMethod("POST");
25                        connection.setRequestProperty("Content-Type", "application/json");
26                        connection.setRequestProperty("Accept", "application/json");
27
28                        connection.setDoInput(true);
29                        connection.setDoOutput(true);
30                        connection.getOutputStream().write(sendJson);
31                        connection.getOutputStream().flush();
32                        connection.getOutputStream().close();
33
34                        connection.connect();
35                        connection.getResponseCode();
36
37                        InputStream in = connection.getInputStream();
38                        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
39                        StringBuilder buf = new StringBuilder();
40                        String line;
41
42                        while ((line = reader.readLine()) != null) {
43                            buf.append(line);
44                        }
45
46                        JSONObject json = new JSONObject(buf.toString());
47
48                        reader.close();
49
50                        connection.disconnect();
51
52                    } catch(Exception e){
53                        e.printStackTrace();
54                    }
55
56                    return i_story_id;
57
58                }
59
60
61                @Override
62                protected void onPreExecute() {
63                    super.onPreExecute();
64                }
65
66                protected void onPostExecute(String result)
67                {
68                    int i_stage_no  = Integer.parseInt(result);
69                    if (story_no == -1)
70                    {
71                        story_no = i_stage_no;
72                    } else {
73                        if (story_no != i_stage_no)
74                        {
75                            Log.d("debug", "reload");
76                            story_no = i_stage_no;
77                            String data = "email=********&password=*************";
78                            String url = "http://192.168.33.10/theater/Mainmenu/view";
79                            myWebView.postUrl(url, data.getBytes());
80
81                        }
82                    }
83                }
84
85
86            }.execute();
87
88        }catch(Exception e){
89            e.printStackTrace();
90        }
91        return story_id;
92}
93

error
12019-12-26 15:04:40.812 19215-19295/com.example.webview_001 W/System.err: java.net.ProtocolException: unexpected end of stream
22019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at com.android.okhttp.internal.http.Http1xStream$FixedLengthSource.read(Http1xStream.java:396)
32019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at com.android.okhttp.okio.RealBufferedSource$1.read(RealBufferedSource.java:371)
42019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:288)
52019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:351)
62019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:180)
72019-12-26 15:04:40.837 19215-19295/com.example.webview_001 W/System.err:     at java.io.InputStreamReader.read(InputStreamReader.java:184)
82019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.io.BufferedReader.fill(BufferedReader.java:172)
92019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.io.BufferedReader.readLine(BufferedReader.java:335)
102019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.io.BufferedReader.readLine(BufferedReader.java:400)
112019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at com.example.webview_001.MainActivity$2.doInBackground(MainActivity.java:145)
122019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at com.example.webview_001.MainActivity$2.doInBackground(MainActivity.java:101)
132019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:333)
142019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
152019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
162019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
172019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
182019-12-26 15:04:40.838 19215-19295/com.example.webview_001 W/System.err:     at java.lang.Thread.run(Thread.java:764)