Static ip

Hi a program I want to use says I need to assign a static ip address and then port forward it.I'm going through a cable modem then on to a router. I know how to do these tasks. My question is once I assign the ip on this my laptop will my desktop pc be affected which is only conected to my cable modem and not through the router

 

You will also need to set up port forwarding from your modem and static IP with the router. The other comp connected to the modem should not be affected. So...

1. Assign a static IP to router.
2. Port Forward on modem to router.
3. Assign Static IP on device
4. Port Forward on router to device

 

Easier to connect both computers to the router, then you will only have to forward ports from router to static IP.

Is there a reason that you cant set it up that way?