I can possibly be of some assistance. Firstly the local IP address should be your computers IP address, so make sure you have a static address configured or have a DHCP reservation setup on your router for you computer. The link below you can find the ports used by Diablo 3.
https://us.battle.net/support/en/art...-configuration (same link as Monk

)
I would create a upload and download rule, but you will probably need the IP ranges for the D3 and Battle.net servers (cant find it anywhere atm), might just be easier for you to setup a rule that prioritise any traffic coming from your PC, what router is this?