What VPN router can restrict access to VPN tunnel via MAC address?

"It sounds like you have a DGFV338 connected to your home DSL line, which bridges your entire home network with the office network. If you have a separate broadband modem, the solution is pretty straightforward--just put another router in between the modem and the DGFV338, and only let your friends connect to this new ""public"" router to get on the Internet.

You probably will also want to configure the public router on a different subnet than both your office network and your private router, because traffic from the private router may have trouble traversing the network otherwise.

Also note that the computers on your private network should be able to access anything on your public network, but computers on the public network should be blocked from the private network unless the DGFV338 is configured to route the other direction. This should be the case already, but you may want to confirm it before allowing anyone onto the public network."