A dumbwaiter carries things between floors out of sight. It is read as messages passing between the conscious and hidden parts of the mind, or as work done for others without being seen.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.