The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Chad Schwitters, the former president of Plug In America, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.
FWIW, most people only have one TEG (Tesla energy gateway), although its not unheard of for someone to have 2 if they have large electrical service (above 200amp). I have never read anything at all about a "serial" connection in a TEG. The wifi connection on a TEG is used for the TEG to connect to the internet (not to communicate with any other devices connected specifically to it, like powerwalls.).
You can connect a TEG via the ethernet hard wired connection, to connect it to the internet. The connection between powerwall and TEG is a specific one via some cable / communication I am unaware of, but its not wifi.
Ok let me expand, I believe the TEG communicates from the current clamp sending unit which has a small aerial on it to the Tesla powerwall which has what is labelled as a gateway connected to it. I don’t want any WiFi in my home for health reasons therefore I want to be able to connect the current clamp to the TEG without the use of WiFi. The gateway communicates via an Ethernet connection to the internet so I can monitor the battery via the app. I hope this is a little clearer.