website returning random 504 and 502 errors

I am getting 502/ 504 errors on the website randomly, and have tried all the methods to debug the issue but unable to fix it When getting 5xx errors, I tried renaming the plugins folder to check if website is loading, and is loading. Then I tried installing each plugin one by one to find the faulty plugin but unable to find any issue as all plugins are being installed successfully but after some time it is throwing 5xx errors. I tried keeping logs for but none are being inserted in the debug.log too ! Any any one please guide on how to troubleshoot the issue ?