OK I think you are correct. I would not be able to put a switch in here since either router could try and connect to the WAN and block the other. I think a router would be better than a switch.
...

The core requirements are:
1. Both subnets can get to the web.
2. One subnet is totally isolated from the other. There's a catch here. It is OK for subnet1 to see subnet 2 but it is not ok for...

Sorry the diagram did not format nicely.
Here is another attempt at describing the network.


WAN -> Modem <--> Switch input port.
Switch Port 1 --> WAN port on router 1.
Switch port 2 --> WAN...

Hello all.
I am wanting to connect two subnets so they can't see each other but each can get out to the web through a common single modem line.
I have two routers but I believe I need another...