This message was posted on behalf of Intel Corporation
The theoretical maximum of 867 Mbps is enabled by 802.11ac using 2 spatial streams, however, the information you provided suggests that your Intel® Dual Band Wireless-AC 8260 is negotiating a 802.11n connection, not 802.11ac.
The connection is a result of the router, OS, computer and adapter combination. The main things you can check for this are the following:
- Go the Device Manager and apply the configuration from the following advisory: http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000005544.html
- Make sure your Windows* OS has any relevant system updates and that your Motherboard BIOS is up-to-date as well.
It is also important to mention that the Intel® PROSet/Wireless WiFi Connection Utility is not available in Windows® 10, since the wireless connections are handled by the OS.