This is the way I was able to get physical appliance information from my gateway:
dmidecode -s system-product-name
That will get you the appliance model. dmidecode has a lot of other options too. Just do this to see all the system strings:
Also just running dmidecode by itself will give you more information than you probably needed. There is a man page for dmidecode that can help you further.
Good info. Alternatively, you can run: mwg-info model
'mwg-info' by itself will list the available commands