The exact change I've made is, from:
$app->redirect(JRoute::_('index.php?option=com_jfbconnect&view=loginregister' . $returnParam), 'Your session timed out. Please try again', 'error');
to:
$link_JFBLogin = JURI::root()."index.php?option=com_jfbconnect&view=loginregister".$returnParam;
$app->redirect($link_JFBLogin,'Your session timed out. Please try again', 'error');
in every redirect, because it was leading to a 505 error. Actually, with your suggestion is everything fine in JFBConnect and in Jlinked too.
I have no menu item named component, and the router functionalities is from sh404sef (but set to joomla router for JFB & JL), never modified.
All is ok now, can't wait to implement Google+ login/registration
Thanks a lot Alzander
bye!