I have been trying to set-up port forwarding for my pc, which is connected per lan to my wifi extender, using different methods:

First tried to port forward the MAC address in my actual router settings (speedport), which did not work, since I can't port forward to a device which is inactive (after speedport, my pc was on and connected to the extender, which was connected to the router).

Second tried to port forward to my Extender, which was marked as active device, but this also did not worked.

Lastly I tried to port forward to a wifi device connected to my extender, since the devices connected per wifi showed up on my speedport page, but this also did not work.

Can anyone tell me why that is ?

I am really in need of the port forwarding since I love doing networking and if this extender does not work I will probably send it back.