When first setting up DyKnow, it is common to see a content filter, proxy, etc getting in the way of communication to the server. This has the effect of students not showing up in Monitor. One particularly confusing situation to see is student showing up in Vision but not in Monitor.
This happens because the DyKnow client runs as the local domain user on Windows. Monitor, however, is running at a very low level on the system and is effectively not considered a domain user. If your network is configured to allow/deny access or to route traffic differently for domain and non-domain users, you need to ensure that you always allow access through to the DyKnow server on each path (authenticated and unauthenticated).