Flutter Socket IO with nodejs - receiving timeout on connection - node.js

Question

I'm using flutter socket io to communicate to my server that's running node/express.
The server code:
var express = require('express');
var bodyParser = require('body-parser')
var app = express();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var mongoose = require('mongoose');
app.use(express.static(__dirname));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}))
var Message = mongoose.model('Message',{
name : String,
message : String
})
app.get('/', (req, res) =>{
res.send("Hello");
});
io.on('connection', () =>{
console.log('a user is connected')
});
var server = http.listen(8080, "<MyServerIP>", () => {
console.log('server is running on port', server.address().port);
});
My Flutter code :
connect() async {
try {
String connectionPoint = "http://<MyServerIP>:8080";
//Connect to Socket.IO
socket = IO.io(
connectionPoint,
OptionBuilder()
.setTransports(['websocket']) // for Flutter or Dart VM
//.disableAutoConnect() // disable auto-connection
//.setExtraHeaders({'id': tokenId}) // optional
.build());
//socket.connect();
socket.onConnecting((data){
print("Connecting");
});
socket.onConnectError((data) {
print("Error Connecting - > $data");
});
socket.onConnectTimeout((data) => null);
socket.onDisconnect((data) => null);
} catch (e) {}
}
When ever i try to connect I'm getting a timeout error that's caught in onConnectError.
The node server is running debian, and I've checked the firewall status:
To Action From
-- ------ ----
27017 ALLOW Anywhere
80 ALLOW Anywhere
3000 ALLOW Anywhere
22 ALLOW Anywhere
Samba ALLOW Anywhere
8080 ALLOW Anywhere
27017 (v6) ALLOW Anywhere (v6)
80 (v6) ALLOW Anywhere (v6)
3000 (v6) ALLOW Anywhere (v6)
22 (v6) ALLOW Anywhere (v6)
Samba (v6) ALLOW Anywhere (v6)
8080 (v6) ALLOW Anywhere (v6)
3000 ALLOW OUT Anywhere
3000 (v6) ALLOW OUT Anywhere (v6)
When I open the url via chrome I'm getting the "Hello" message.
When I try netcat "nc -vz MyServerIp 8080 and I'm getting a success in connecting. I've also checked my local firewall and I've allowed all connections for qemu to my MyServerIp.
Just need some help as to try to work out why I'm getting the timeout and whether there are any ways to debug this ?
##Edit:
MyServerIP is the actual server ip of my server.
##Edit 2:
I used my device to test whether it was something that was local issue to the android emulator. And, I received the same error (I also took the device off my wifi to eliminate any local firewall issues). I'm assuming that this would mean that it has something to do with my server.

Answer 1

The issue being faced was due to the mis-match between the server version and the package being installed with Flutter. The version on the server was > 3. The latest version installed for flutter is not compatible with a server version. There is a beta version that needs to be used.
At the moment there are two options :
Option 1: Downgrade the servers version so that its compatible.
Option 2 use the beta version. (this is the option I took).
Update pubspec.yaml to socket_io_client: ^2.0.0-beta.2 and it connects.