First you write the connection is to the ISP, then you write it's connection is to a router. Those are two different connections.
Remember I can't see your setup but if you want to bridge the connection that bridge varies with each OS. You would be conversant with your OS.
I have two lan cards. I use first one to connect to Internet via connection to ISP, I share this connection to a second lan card, which I use as a WAN connection to router. So, Main PC have an Internet Connection, router share this connection via WiFi and LAN connections to other PCs. But here's a problem, any PC that is connected to Internet using router, cannot access Main PC and Main PC cannot access router web interface. Is there any way to fix this?