We have a router with only two interfaces. Could you use it to make another subnet on our LAN when it will not be the gateway address on everyone's PC? The Gateway address is a modem to the internet. I can see setting the router as a gateway address if it had 3 interfaces, one for each subnet and one for the internet, but this one only has two. How would you do this? Thanks!
What exactly are you trying to do - the router is just that "a router" so if you run another IP subnet, on the other interface - you can still route to the modem via the default gateway static route?
You can tell all the PC's on the 2xIP (router ethernet interfaces) subnets that the default gateway is the router on the specific ethernet interfaces, and the default gateway for the router is the modem.