The schema is near useless, but only if:
1) Really one single lan cable connect PC1 with Router, and a single cable Router and PC2?
Why do not link directly the 2 PC?
2) Why not simply change the IP of PC?
3) Why not simply add another IP to PC?
You can not NAT anything if the Router if is not the default Gateway or if the two PC have another LAN connection with it's own gateway.
export the config with
and after removed the private data, paste on forum.
Also paste both IPv4 configuration of the two PC.