IP passthrough and network security.

No. 

Thanks 

Thanks 

do I lose security scanning provided through AT&T

If you are talking about these features:

Smart Home Manager will let you know about:

• Device weaknesses
• Known default device passwords (often found on printers and scanners)

then yes you would lose this ability for any device connected to the Gateway via the IP Passthrough device (or any router connected and operating as a router vs. as an access point, switch or extender).

However, the other features of Smart Internet Security should function normally as @browndk26  indicates.