OK /g/, hopefully you can help me here because how do I networking?

I want to forward a port to one of devices. My devices are assigned static IP by the gateway.
I tried port forwarding a port both at gateway (which is a multi purpose router) and the router itself (likewise a multi-purpose router which I used as a gateway with previous ISP). The port is apparently still closed.

Here is what I thought might solve the problem. Have gateway pass everything without an exception to the router and have the router firewall forward and filter everything. The problem is that they gateway and the router don't see each other even though they are physically plugged into each other.

Any ideas? I probably am going full retard somewhere along the line so help to point it out please

pic related