Good that you have doublechecked the netmasks, since that could in some situations create the effect you see. You have also verified the NAS stations mask as well?
When you run tcpdump from the VM on the interface attached to vSwitch1, do you see any traffic at all? If having a tcpdump filter like "icmp or arp", (and clear the guest OS arp cache first), do you see the ARP request broadcast leave the VM?