If it's a regular modem, it will only give you one IP. Connect the Router to the Modem, and the switch to the router. Anything connected to the Router will be on a different network than anything connected to the switch the way you have it setup. And the Modem will only give one IP to your devices unless it's a Modem/Router combination. If you want to use the router as just a regular switch, turn off DHCP and NAT functions in it.