I just managed to fix this problem by replacing the Router's firmware to a newer one.
After dealing with this problem for almost a year now with the OEM card (6235) and a new one I purchased N7260 I realized it cannot be a problem with the cards/drivers simply because they are 2 different chip sets.
My router is a Linksys E1200 HWv1 which worked fine with the PC's I had in the pas but with this one it was a nightmare of disconnects with Skype. My connections were at 144 the highest and 12 the worst scenario which looked to be a 56k modem connection (arrrrg)
I installed the DD-WRT firmware (available for many brands and models) and after I did the upgrade the connection has been fixed at 300mbps I tested the different drivers and I am actually using 16.8.0.6.
My recommendation is upgrade your routers firmware and if not possible change the router to a newer one as I am completely sure that the problem is the router's firmware.