The error message "404 Page Not Found" will most likely appear in your browser when you have not completely migrated your WordPress site from one server to another. It is usually the result of a missing .htaccess file.
When the .htaccess file is missing, permalinks will not work, and you will get Page Not Found errors.
To resolve these errors, make sure your SFTP client is set to show hidden files.
Then, drag and drop your .htaccess file from the app's web root directory on your old server to the app's public folder on your new server.
Your previous permalink structure should now be restored.