A modem stands for the link that lets you connect with the wider world. Tradition reads problems with it as feeling cut off, or as communication that will not get through.
Does the traditional reading fit your dream, or did it mean something else to you?
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.