Try to relocate your router to a central location in your home. You will likely see an improvement in Wifi speed. Also, any Wifi connection has some degree of degradation of speed due to distance and interferences. An 802.11ac router may improve Wifi speed, however, you may not get zero loss in speed for Wifi.
From having issues with the internet connection via WiFi to my 4k Apple tv, I’m looking to optimise the WiFi in the house. Using a D-Link DIR-845L, internet speed on the laptop via Ethernet cable is averaging 14-15Mbps where as a speed test of the WiFi averages 8-10Mbps both next to where the Apple TV is and right next to the D-Link. Question is, is this amount of loss in speed to be expected? If we were to upgrade to a router with 802.11ac could we expect zero loss in speed?

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