Port forwarding using unmanaged switch

I moved into a new house and it has Ethernet cables run into each room already. Where each of these cables terminated was in the garage, so instead of having the Wi-Fi modem in the garage I just used a cheap, unmanaged switch so I can run Internet to each room without running through the Wi-Fi router. I’m now wondering how IP’s work with the unmanaged switch and if port forwarding is available. At the moment the PC plugged into the switch has the same IPv4 as my public IP which I understand is because IPv4 is given through the router and with an unmanaged switch it won’t, but does this mean I

Question by Noah Oosterbeek on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.