Not able to connect to Socket.io on AWS EC2: NodeJS+NGINX+Letsencrypt

I am trying to connect to the Socket.io server. The server is in NOdeJS. Hosted on AWS EC2 with letsecrypt certificate enabled.I am using https://amritb.github.io/socketio-client-tool/ to test the connection. But it is giving error:

index.js:83 WebSocket connection to 'wss://lms.wordsmaya.com/socket.io/?EIO=3&transport=websocket' failed: Error during WebSocket handshake: Unexpected response code: 200n.doOpen @ index.js:83n.open @ index.js:83n.open @ index.js:83n @ index.js:83n @ index.js:83n.open.n.connect @ index.js:83n @ index.js:83n @ index.js:83n @ index.js:83(anonymous) @ app.js:66dispatch @ jquery.min.js:3r.handle @ jquery.min.js:33index.js:83 WebSocket connection to 'wss://lms.wordsmaya.com/socket.io/?EIO=3&transport=websocket' failed: Error during WebSocket handshake: Unexpected response code: 200

I have opened the appropriate ports in Security Group. Also the NGINX configured as mentioned here:

With all this configuration I am not able to connect to Socket.io server. What could be the issue?It is happening when we hosted the code on AWS EC2. On Azure webapp the same code is working.