I have the same issue.
I am using WBR-1310 and MBP. Especially after I turn off my MBP for couple of hours and after I turn on my MBP, it just can't get ip from my router.
My router is using DHCP and it is B2 version with firmware update 2.02.
The only way to make it work is to restart the router.
I hope you guys can figure it out. Thanks!