Hello,
I bought a Dell Inspiron 15 3511 laptop for a client.
For two days I couldn't get the wireless network card to work with any manually downloaded driver, so I took it to the distributor. The technical support there solved it in 5 minutes, simply saying that I had to look for the drivers by the Service Tag of the equipment on the dell.com website. It's worth a try, although the driver packages coincide by all proprieties (size, checksum, MD5, etc.).
Anyway, it's good to know that there is a simple and quick solution. We still don't know exactly which one it is.
Good luck!