Some time website issue 502 timeout

I install the Cloudflare on this site [techradarto](https://www.techradarto.com) and enable
ssl certificate , but some time issue on open the site its showing 502 error and site is not
load what is the issue ?
check with hosting its perfect . Cloudflare ssl also perfect where is the issue i cant solve .

The 502/504 errors are caused by a problem connecting to an upstream server - meaning your server is trying to initiate a process and this fails to work as expected or times out. In most cases of 502 / 504 errors, back-end servers are not communicating correctly. When this happens, you will see color page with Cloudflare branding and the Error 502 Bad Gateway or Error 504 Gateway Timeout. Review this Community Tip for fixing 502 or 504 gateway errors.

I checked your site and I currently do not observe a 502 error. If the error occurs again, can you please provide a screenshot of the error?