Comcast allows the home user to buy a second IP address. I bought a Cisco switch (I don't know whether it's Layer 2 or Layer 3) based on some advice I got. One port of the switch is connected to my router, which in turn serves my LAN, and another port is connected to a standalone computer. A third port is connected to my modem. I confirmed that both the router and the standalone computer get different external-facing IP addresses.
This setup has worked for me for months. However, I recently got a speed upgrade from Comcast and now only one node in the switch works at a time. They're sending a technician out to "disable a trap."
My question is, how is this setup able to work in the first place?