RNFetchBlob can not download apk, But in the Browser the url can dowload file

I develop a react-native app, for android, I use the RNFetchBlob to download the APK. and in android, RNFetchBlob uses OkHttp library to download the file. But the APK can not download. when I put the link in android, it can download the file successfully.

I try to replace it us the other URL, RNFetchBlob can download the file.

But my URL is a simple url: http://host:port/AppDownLoad/publish/some.apk

the RNFetchBlob config is the below:

 RNFetchBlob.config({
      path: dirs.DCIMDir + "/Some.apk",
      timeout:180000, //超时三分钟
    })
      .fetch("GET", APK_URL)
      .progress({ count: 10 }, (received, total) => {
        let currentProgress = received / total;
      })
      .then(res => {

        if(res.respInfo.timeout){
          Linking.openURL(APKURL)
          return;
        }
        android.actionViewIntent(
         res.path(),
        "application/vnd.android.package-archive"
        );
      })
      .catch(error => {
        console.log(error); 
        // Linking.openURL(APKURL)
      });

the third library OkHttp source code is:

OkHttpClient.Builder clientBuilder;
if (this.options.trusty) {
                clientBuilder = RNFetchBlobUtils.getUnsafeOkHttpClient(client);
            } else {
                clientBuilder = client.newBuilder();
            }

            final Request.Builder builder = new Request.Builder();
            try {
                builder.url(new URL(url));
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            builder.method("GET", null);
            final Request req = builder.build();
            clientBuilder.connectionPool(pool);
            clientBuilder.retryOnConnectionFailure(false);
            clientBuilder.followRedirects(options.followRedirect);
            clientBuilder.followSslRedirects(options.followRedirect);
            clientBuilder.retryOnConnectionFailure(true);

            OkHttpClient client = enableTls12OnPreLollipop(clientBuilder).build();

            Call call =  client.newCall(req);
            taskTable.put(taskId, call);
            call.enqueue(new okhttp3.Callback(),{callback}

Could anyone tell me why?