On my 3521 I have the same problem as many others with intermittent wifi connectivity. I my attempts to fix it I inadvertently deleted the driver for the first (Dell) network adapter and it now does not appear in Device Manager. Only the Realtek one is there.
Firstly how can I get it back?
Secondly is there a fix to get wifi to work reliably. Has Dell ever provided a solution?
Many Thanks for your help