Please refer to the other thread on "Note 2" for explanation.
As you have only selected one 802.11ac instead of all.
Maybe you have the IPv6 feature enabled in your laptop or PC. IPv6 makes your whole system slower, make sure you uncheck the checkbox for the IPv6 feature in settings.
Keep it away from metallic objects, metal hinders with the signals and increase interference.
Or you can download the latest firmware from its official website.
If still not working visit Linksys Support Number