Getting randomly 524 error

We are facing a very strange issue with CloudFlare. We get randomly 524 error to certain of our customers. We executed all the suggestions mentioned in the below discussion but nothing wrong at the server end.

Exploring more stuff on google I came across that it is working well if your open private or incognito window of browser. Here is the link for your reference.

I am not sure why from private window, request lend well while not from the original up and running browser window.

Request you to suggest a solution to over come this challenge as it is very difficult for customer to work on the system once this issue happens with the browser page.