go to Network and sharing center--change adapter settings
--right click on the wireless card--properties--configure--advanced--wireless mode
there you can change it

Thanks very much for your response. After making the change and rebooting, I now have it set to 802.11ac however, the TP-LINK utility is still telling me 802.11a is the protocol. I wonder if it's really 802.11ac but it is just displaying wrong? The disappointing thing is that the TP-LINK utility says I'm connected at 54 Mbps. When I do the Comcast network speed utility I get 25 Mbps. I'm going to remove the drivers and the TP-LINK utility and start over again with just the Windows driver and see if that makes a difference.

RedZinger wrote

Thanks very much for your response. After making the change and rebooting, I now have it set to 802.11ac however, the TP-LINK utility is still telling me 802.11a is the protocol. I wonder if it's really 802.11ac but it is just displaying wrong? The disappointing thing is that the TP-LINK utility says I'm connected at 54 Mbps. When I do the Comcast network speed utility I get 25 Mbps. I'm going to remove the drivers and the TP-LINK utility and start over again with just the Windows driver and see if that makes a difference.

also you can search the driver on google depending on the chipset

Thanks. Windows did not automatically install a driver so I did search for and found a driver online on the TP-Link web site and used it. Same problem repeated. 802.11ac protocol is specific to 5 Ghz so I tried 802.11n at 2.4 Ghz and it worked perfectly. According to the TP-Link utility I was connected at 185 Mpbs and according to the Xfinity speedtest I am getting 65 to 70 Mbps download speeds. It is only when I switch to 5 Ghz that I have problems with speed and connecting. My computer is dual boot ubuntu/Windows 10 so I then installed the adapter in my ubuntu partition. Same results. Only the 2.4 Ghz worked and yielding the same speeds. So what I'm concluding is that the conditions in my house are not conducive to connecting at 5 Ghz. My router is at the bottom of a stairwell so the wireless transmission has to go up the stairs and straight into a bedroom where my computer is on a desk near the door. There may be something blocking the signal. I think I'll keep it set at 802.11n at 2.4 Ghz for now until I can run a cable upstairs from the router. Nothing works better than a hard-wired connection.