Topology is only a Point to point network on Wifi, and the cellphone is the point that then connects to internet, just that the cellphone may change.so one point may dissapear and another point may appear.
The condition to let the router use the WIFI are the SSID and the security setting.
Not really complex, and alot easier than in automotive needs.
What we try to accomplish is to remove all open points on the critical issue list, then router can be installed. Or you want to know whats the purpose of the reachable VPN-Endpoint ? We need it to be able to connect Programming Envoirment to ECU in case of malfunctioning.
Just some simple 360°testing before selling a machine without the old router we use now. (reason to change router we use would be : Mobile network)