Port forwarding

So I tried forwarding a port but it did not seem to work (tested with PFPortChecker: "Your port is NOT OPEN or not reachable").

Laptop: Acer V3-772G
OS: Windows 8.1
Router: FritzBox 7390 (with an Ethernet Switch, Netgear GS605)
Firewall: Windows Firewall disabled. Using COMODO, but switched it off to see if it would change anything.

So first I set up a static IP and then forwarded the port (TCP/UDP).
Does the Ethernet Switch act as a second router? I don't think so, but I read something about if you're using more routers and "Double NAT", where you need to chain port forward.

portforward.com has all of the info you need to know. You do the forwarding through the router. The only way that you would have Double NAT, is if you have two routers on the network.