Access point+wireless MAC filtering?
Refer to the post here to configure it as an access point.
http://forum.tp-link.com/showthread.php?78963-Can-someone-post-their-settings-config-file-for-Archer-c7-v2-as-an-AP&p=156734&viewfull=1#post156734

You can configure wireless MAC filtering following the guide below.
http://www.tp-link.com/en/faq-324.html

As far as I can tell, this will completely block the specified Wireless device from accessing the network entirely. I want to give it access to the gateway (another router) and no other internal network devices. I can imagine how I would do this with iptables, but I can't see how I can do this with the Archer C7.

I want to give it access to the gateway (another router) and no other internal network devices.
Like guest network?

If so, the problem is that you cannot configure C7 as an AP because you have to " Allow Guest to Access My Local Network” to access internet.

Tony Seaford wrote

I want to give it access to the gateway (another router) and no other internal network devices.
Like guest network?

If so, the problem is that you cannot configure C7 as an AP because you have to " Allow Guest to Access My Local Network” to access internet.

That's why I was trying using the Access Control rules, which seem to be completely ineffective when the C7 is acting as an access point. I guess I'll just have to get a better wireless router.