If you are recording traffic on the hub, you will only see traffic from hosts on the hub and the
router's interface address (IP address). This is because layer 2 functions differently from layer 3.
(Don't worry about the differences or anything, thats a later course).

Basically, just know that if there is a host on another SUBNET (i.e, network) than you will not be able
to record their MAC address, and in most cases you will not record their IP address either.