The WZR-HP-301NH is a router that is only available in our Japanese market.
Unfortunately, these forums are for US and Canada market Buffalo models, so any information we will be able to supply concerning products from other markets will be very little.
According to the Japanese Buffalo site, nikop84 is correct, the WZR-HP-G301NH is a re-designed model with an eye for power savings, up to 69% of previous models.