What does not work exactly? … I know you said the Connections menu does not show. Is there more?
Have you installed the Connections plugin? If you do, do you have any of the bestwebsoft plugins installed? It use to be that a few of their plugins would “knock” the Connections menu item off the admin menus. I do not know if that is still longer the case or not, but it is a possibility. If you have a bestwebsoft plugin installed and Connections is installed, then you can install the free Toolbar extension. It’ll add the Connections menus to the admin bar.