I have my Networking [L] plates on and enjoy learning about networks. This is my understanding.
Unlike in a Hub environment, where all devices on the Hub get an all stations broadcast of packets on the network and then take their own, I've had the impression in a Switch LAN that any device that communicates directly with another device within the switch or an external LAN/WAN network does so on a one-to-one basis, Unicast, therefore must have a unique MAC address otherwise the switch doesn't know who to connect to. # The 7 additional devices on the switch have to be internally switched to the Uplink MAC first in order for them to escape to their external destination and that information must also include the target or destination IP address and maybe MAC address that the PC or device wishes to be connected to. Assume that is how evidence is collected used for prosecuting bad guys.
The Cisco switch I have is a SF110D-08HP - its MAC address is on a separate sticker underneath away from the main sticker, which is unusual. Generally these addresses are usually printed on the main sticker along with Serial Number and Factory Part number for stock reference.
# the Modem which also contains a LAN switch function is also capable to broadcasting specified groups or all ports within its domain using Multicast - I think from previous readings that are bit a hazy, the broadcast address is either the last or the second last one in the IP range of the modem - probably varies from vendors.
thanks for the help everyone, I got this resolved eventually by getting onto the Optus support through the phone (2hrs waiting) and a technician came on site and provided me with the missing piece of the puzzle, a sagemcom router, once plugged in it's all working like a dream. Amazing when you have the right pieces to the puzzle.