In the staging site, you would deactivate all plugins (including Yoast SEO) and switch to a default theme. Go to https://greentecct.com/2019/01/press-release/ in a browser to ensure the page loads the content you expect to see (ignore any styling issues for now). If the page does not loads content, activate any required plugins/themes to display the content. Once the page loads content, follow these steps:
Go to https://httpstatus.io/
Enter https://greentecct.com/2019/01/press-release/
Click ‘Check’
What status code is shown for the page?
If the code is 200, activate one plugin and clear cache. I usually start at the top of the plugin list and work down the list. Repeat the steps above until the code returned is 404. Whatever plugin was activated immediately before the status shows a 404, is likely what causes the 404. If you activate all plugins and the 404 hasn’t appeared, the issue is most likely your theme.
To confirm, disable everything again and start over, this time activating the suspected cause (plugin or theme) of the 404 first and then test the status with the steps above.
The idea is to find the bare minimum setup required to get the 404 so you can contact the support team for the plugin/theme that can be assist you in solving it.
This article may help: How to check for conflicts
