Wp-Admin FTPS Connection Error unlike Filezilla

In FileZilla you use SFTP connection to access your server and it works (because it was setup on server). But in wp-admin you use FTPS connection, which is probably doesn’t setup on server. Pay attention that SFTP != FTPS.

A solution could be to change File System method in your wp-config.php file by adding FS_METHOD constant with direct value, it will change upgrade method from ftp to direct:

define( 'FS_METHOD', 'direct' );

Another solution could be correct configuration of your hosting server to allow you FTPS connections.

And finally check file permissions of wp-content folder. It should be writable for user, by which you run your site.