Android App & FTP

So I am trying the new Cyanogenmod 9 (Android 4.0) for SGS2 and since the MTP (file transfer via USB) is broken I want to use this software (and the likes of it) Software Data Cable.

The thing is I have tried my Laptop (macbook pro) and desktop (Ubuntu) both do not open the FTP address that the app generates. So there has to be something wrong with the phone or the router (probably the router and its ports). I am using the app's default port (8888) and do not know the correct way of opening up that port on my router.

Can Anyone please help?