I recall port forwarding on the superhub worked OK for me.
However, lately I've been using an asus rt n16 flashed with tomatousb. The other day I was quite depressed to find that port forwarding had stopped working.
I managed to retrieve the situation by clearing the NVRAM.
On the superhub the nearest equivalent is resetting to factory defaults. If you are still getting problems and are confident you've done everything right then you must have a faulty superhub.