@FpgaEd As I understand it, outside of the primary router node, it is possible the walls of the guest network can come down due to the fact that any other equipment relaying traffic on the network must preserve VLAN tagging. That is how the guest network traffic is kept separate.

Currently there is no way to define a separate subnet/DHCP scope for the guest network. I suspect they're all on the same subnet and that's why it's possible without VLAN tag preservation for the traffic to cross talk. 

I guess you have to appreciate these are residential class and were meant to be simple and straightforward for the everyday home user.

You may want to see if the Omada series is an option. Similar deal but that's their more mid range offering for business type scenarios. I haven't used them but I imagine they're more along the lines of what Ubiquti, Ruckus, Datto, Meraki etc have out there- and I'm sure probably witn the price tag to match, I imagine. But you want a more robust product, they want a more robust wallet. Lol...

  @YourStupid I appreciate you taking your time to reply. I understand and agree with your assertions.