Unhandled Exception: WebSocketException: Connection to 'http://10.5.11.88:7777/socketcluster/#' was not upgraded to websocket - flutter

Question

Here is my Client code and server is in c++. But when i am trying to connect this client to server it is throwing an error that websocket is not upgrading. The server is running i have checked with js client.
Code for client
import 'package:socketcluster_client/socketcluster_client.dart';
import 'dart:async';
class MyListener extends BasicListener {
#override
void onAuthentication(Socket socket, bool status) {
print('onAuthentication: socket $socket status $status');
}
#override
void onConnectError(Socket socket, e) {
print('onConnectError: socket $socket e $e');
}
#override
void onConnected(Socket socket) {
print('onConnected: socket $socket');
new Timer.periodic(const Duration(seconds: 2), (_) {
print('Attempting to send');
socket.emit('sampleClientEvent',
{'message': 'This is an object with a message property'});
});
}
#override
void onDisconnected(Socket socket) {
print('onDisconnected: socket $socket');
}
#override
void onSetAuthToken(String token, Socket socket) {
print('onSetAuthToken: socket $socket token $token');
socket.authToken = token;
}
}
main() async {
var socket = await Socket.connect('ws://10.5.11.88:7777/socketcluster/',
listener: new MyListener());
socket.on('rand', (name, data, ack) {
print('got message $data from event $name');
ack(name, 'No error', 'Hi there buddy');
});
}
I have tried https://github.com/flutter/flutter/issues/11444 but it is not working.
Error Log
Launching lib\main.dart on AOSP on IA Emulator in debug mode...
Running Gradle task 'assembleDebug'...
√ Built build\app\outputs\apk\debug\app-debug.apk.
Installing build\app\outputs\apk\app.apk...
Syncing files to device AOSP on IA Emulator...
E/flutter ( 5399): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled
Exception: WebSocketException: Connection to
'http://10.5.11.88:7777/socketcluster/#' was not upgraded to websocket
E/flutter ( 5399): #0 _WebSocketImpl.connect.<anonymous closure>.error
(dart:_http/websocket_impl.dart:1054:9)
E/flutter ( 5399): #1 _WebSocketImpl.connect.<anonymous closure>
(dart:_http/websocket_impl.dart:1063:14)
E/flutter ( 5399): #2 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 5399): #3 _CustomZone.runUnary
(dart:async/zone.dart:1031:19)
E/flutter ( 5399): #4 _FutureListener.handleValue
(dart:async/future_impl.dart:139:18)
E/flutter ( 5399): #5 Future._propagateToListeners.handleValueCallback
(dart:async/future_impl.dart:680:45)
E/flutter ( 5399): #6 Future._propagateToListeners
(dart:async/future_impl.dart:709:32)
E/flutter ( 5399): #7 Future._completeWithValue
(dart:async/future_impl.dart:524:5)
E/flutter ( 5399): #8 Future.wait.<anonymous closure>
(dart:async/future.dart:400:22)
E/flutter ( 5399): #9 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 5399): #10 _CustomZone.runUnary
(dart:async/zone.dart:1031:19)
E/flutter ( 5399): #11 _FutureListener.handleValue
(dart:async/future_impl.dart:139:18)
E/flutter ( 5399): #12 Future._propagateToListeners.handleValueCallback
(dart:async/future_impl.dart:680:45)
E/flutter ( 5399): #13 Future._propagateToListeners
(dart:async/future_impl.dart:709:32)
E/flutter ( 5399): #14 Future._completeWithValue
(dart:async/future_impl.dart:524:5)
E/flutter ( 5399): #15 Future._asyncComplete.<anonymous closure>
(dart:async/future_impl.dart:554:7)
E/flutter ( 5399): #16 _rootRun (dart:async/zone.dart:1126:13)
E/flutter ( 5399): #17 _CustomZone.run (dart:async/zone.dart:1023:19)
E/flutter ( 5399): #18 _CustomZone.runGuarded
(dart:async/zone.dart:925:7)
E/flutter ( 5399): #19 _CustomZone.bindCallbackGuarded.<anonymous
closure> (dart:async/zone.dart:965:23)
E/flutter ( 5399): #20 _microtaskLoop
(dart:async/schedule_microtask.dart:43:21)
E/flutter ( 5399): #21 _startMicrotaskLoop
(dart:async/schedule_microtask.dart:52:5)
E/flutter ( 5399):

Answer 1

Actually strict application load balancer policy was applied on AWS/server
Relaxing it solved the issue