Have reviewed your install. Your non-SEF login redirect URL should've been set to the following.
index.php?option=com_content&view=article&id=20&Itemid=162
I've configured this for you in both login modules. It appears to work perfectly fine in the top login module and on the login page.
Also you're using Joomla SEO without URL Rewriting. This causes Joomla to have to rewrite URLs and prefix with index.php and isn't very reliable. I suggest configuring your htaccess file and enabling URL Rewriting for more reliable SEF URLs.