Have you added the switch itself (and its ports- not interfaces, but UDT ports) to UDT? It will only scan devices and ports that you specify, so if you only have interfaces enabled it will not show you port data on them. The switches need to be added as layer 2 devices to UDT as well. The router needs to be a layer 3 device in there, but judging by you getting data about what router has the MAC in ARP, I'm guessing that part was already done.
If you follow the Getting Started type resource in UDT, it should walk you through this.
Let me know if this helps.