@AndreasR 

If you log into the powerline adapter with your web browser, go to the guest network settings, and make sure to disable the ability to talk to local devices. You coudl find out the powerlines IP address by looking in the DHCP client list in the Archer C7.

Hello Tony,

thanks for your quick answer. On my extender, these settings are already configured as follows:

"Allow guests to see each other" - unchecked

"Do not allow guests to manage..." - checked

"Automatic disable after ..." - unchecked

With these settings, I can still access devices connected to the router from devices connected to the extender's guest network. There is no option "Allow guests to access my local network" which I could simply uncheck. This option does indeed exist in the configuration settings of the router, but it is absent in the configuration of the extender.

@AndreasR 

I got some additional information.

The guest network on the powerline will not keep traffic from your local network since the powerline is working off of the LAN of the C7. The powerline is not able to "route" traffic as it is not a router, but more or less a AP. So with the guest features it is more of a feature to have another network to connect to which is why the option to not allow access to local devices is not there where it is for the C7.

So in the end it is not possible to limit local access if connecting to a powerline adapters wireless network.

I see. Thank you for the clarification. 

Perhaps you should make this clear in the documentation as well. Currently, the guest network is described as a security feature:

Chapter 3.9

"I want to: Create a network for my guests, providing internet access for them

 while at the same time limit the network authorities for guests to ensure network

 security and privacy."

I think this is somewhat misleading. People may think their network is shielded from their guests, which is not the case.

@AndreasR 

Your feedback can certainly be forwarded.

Thank you.