It’s very annoying for years, having notebooks (yes, two!) with Intel Dual Band AC while your router still in b/g/n technology. The connection is almost unusable since it will almost drop all the time and sudden disconnect. Surf around dozens of sites and suggestions, nothing works. Buying dual band wireless AC router is not an option, still expensive for my tight wallet, but it really will solve the problem since my office use it.
Till yesterday I found something interesting, worth to try. I downgrade the router’s speed to b/g only and yes! The AC Wi-Fi works flawlessly. Don’t know why, but it really works.
For your reference, my two notebooks are Acer Aspire V3-371 and Lenovo Yoga 720-13IKB while the home router is Dlink DIR 612 and office routers are Aruba AP-205.