I want to connect a home/SOHO network to the Internet, do I need a router ?

not best options
here is probel is not clear in usering

You can get additional IPs from your ISP, you can use some NAT/PAT software, or you can use a router, all of those options work and the cost is comparable.
We strongly recommend using a hardware router with firewall features and a built-in switch, probably even wireless capabilities.
Why a router, you might ask - A software solution would require one computer to act as a server for the other clients, and getting additional IPs from your ISP usually increases your monthly Internet cost. In addition, both alternative methods do nothing to secure your home/SOHO network.