I have this error when i login in OA Enterprise "ERROR - Unable to retrieve config from OAC (Opmantek::OaeController::index)." , and i can't see any of my devices.
When i login in OA Community it shows me the "404 Page not Found" error.
Just to clarify, AFTER you login into OA Community, or the login page shows a 404?
Sounds like OA Community isn't running at all.
Maybe check your apache and/or php error logs.