Nodejs & Mongodb-getting 504 gateway timeout error

Question

I have been getting 504 gateway time out error after around 30-40 secs while logging in the front end website. first I thought it must be MongoDB error as Mongoose new version have some changes like findOne do not take any callbacks, though I fixed that error. But still, I am getting this 504 error in production. I checked my endpoints and it is working fine in development, I am able to login/signup using Postman. I even put try..catch in every endpoints for the error.

I am using express with MongoDB/Mongoose and my hosted the backend in AWS EC2. I am getting this following error in my console log.

Object { .... message: "Request aborted", name: "AxiosError", code: "ECONNABORTED", config: {…}, request: XMLHttpRequest }
​
code: "ECONNABORTED"
​
config: Object { timeout: 0, xsrfCookieName: "XSRF-TOKEN", xsrfHeaderName: "X-XSRF-TOKEN", … }
​
message: "Request aborted"
​
name: "AxiosError"
​
request: XMLHttpRequest { readyState: 0, timeout: 0, withCredentials: true, … }
​....```

I've tried to increase the timeout value in my back-end

var server = app.listen(5000, () => {   console.log("Server started on port 5000"); });  
server.timeout = 120000;

I really not able to understand that is this a back-end issue or the server issue.