Could it be that you have a combined wifi and Bluetooth card or chip in your laptop? If so, often you can find that there is only one aerial in there and they both share it. Try turning off Bluetooth completely, that could well transform your wifi connection.
Are you using any USB3 devices on your laptop? Or even a USB2 device plugged into a USB3 port? USB3 puts out an unholy amount of RF interference due to the spec being poorly designed, and that can and does interfere with any 2.4GHz signal near by. Unplug everything from the USB3 system on your laptop and try again. Of course, 5GHz networking dodges this problem but is not a reasonable work-around in many situations.
Just some ideas. Of course, checking out firmware and driver update possibilities is a given.