I am having the same problem and I believe I have found the cause.
Like many Dell 7559 owners I began having issues with the left hinge on the cover/ monitor. The screws and the threaded inserts have pulled out from the plastic lower case.
The white primary and black secondary antenna wires route through or near this hinge and are now broken. Plain as day they are both severed and inside the monitor side of the hinge.
I am now trying to figure out were the end of these wires are supposed to attach. Not sure if they just got wrapped around the axle (literally) of the left hinge or are the connected to it by design.
Lousy design flaw. Dell should admit this is common and fix it for free.
Can anyone point me to a diagram or picture of where the antenna wire connects on the end opposite of the the wireless card?
Try connecting to another WiFi network and see if that continues to be an issue.
same. It has the same problem