Update:
I was still experiencing issues with the Intel Centrino 6235-N and since I needed Bluetooth as well I replaced the card with an Intel AC-7260 and I have no more dropouts. I also had the same experience with another wireless card Realtek that I had to change. For me as far as I can tell now, if you experience dropouts issues and rule out that the router is not defective, then we should be able to RMA the card, and this is what I am going to do with Intel, I want a replacement because my unit is defective.
