404 Error Log

404 indicates failure to communicate with the server. Reasons for this failure to communicate with the server can vary.
– it could be configuration issue
– it could be memory issue
– it could be permalinks issue, try reviewing this: How to fix 404 error when using Pretty Permalinks?
– it could be optimization issue
– it could be a conflict with plugin: try resetting the plugin folder ; https://www.wpbeginner.com/plugins/how-to-deactivate-all-plugins-when-not-able-to-access-wp-admin/
– it could be a conflict with theme: try switching to the default theme for a moment via FTP and see if that resolves the issue.
– check for .htaccess file presence and check if the default wordpress mod-rewrite code is there or not. There are times when .htaccess file is not writable or gotten deleted
– Check the server error log for your hosting account for any specific error message. Ask your webhost for assistance to locate them.