Hi Xenofon,
If you are wanting to use the B2 in the 'normal' way (like the rest of us users), then you don't need to set up port forwarding rules at all.
Port forwarding is only required for incoming network connection requests (i.e. someone outside of your home network is connecting into your network)
The B2 is only making outgoing network requests.
The BT router should, in its standard setup, allow the B2 to connect to the internet and make a connection to the Brennan update website. Port forwarding is not needed for this function.
Port forwarding is not required for the B2 to connect to the '
musicbrainz.org' CD lookup database either.
If you do need to access the B2 from outside of your home network, then the two internal port number ranges than I am aware of are Port 80 for WEBUI browser access and Port 22 for ssh SecureShell access (this is if you need Linux access).
Going back to your basic problem, you seem to have established a WiFi connection from the B2 to the router. If your B2 is displaying an IP address of something like '192.168.1.xxx' then the router has issued a suitable IP address to the B2. At this point, you can close down the BT Manager software, no more configuration setup is needed for the router.
From your PC, open up your web browser and type the following URL into the address bar (without the quotes)
Does the PC screen display the B2 menus?
Regards,
Peter.