Two Networks On One Modem

If you need to isolate two networks from each other but still use the same single internet access you could hook one router to another and give the second router a different ip address eg. 192.168.2.1. But this causes a double NAT negotiation and possible problem. It is better to connect the modem to a switch along with the two routers attached to the same switch. Each router has its own IP and are otherwise set up normally.