Your router uses NAT (network address translation) to share a single IP, allocated to your internet connection, among many clients, such as your gaming PC.
So what you are attempting is not going to work.
Those Ethernet splitters also don't let you pass the input signal to more than one output at a time - you couldn't have the router and the PC on at the same time.
Yup, need a switch if you want to have multiple outputs
Your router uses NAT (network address translation) to share a single IP, allocated to your internet connection, among many clients, such as your gaming PC.
So what you are attempting is not going to work.
Those Ethernet splitters also don't let you pass the input signal to more than one output at a time - you couldn't have the router and the PC on at the same time.
Yup, need a switch if you want to have multiple outputs
Or another router to act as a switch