Dell Wireless 1704 problem

I bought the new Inspiron 3721 with this wifi / bluetooth 1704.

The wifi speed is decreasing all the time until lose the connection

I've updated the latest drivers: 6.30.59.74 A03

I have read in this forum that many people have the same problem with this card

I configured the card as suggested to other people but no solution

Any solution from Dell?

I'm with Windows 8

sorry for my english