This message was posted on behalf of Intel Corporation
In circumstances such as this one you have presented, it is possible that files from a previous wireless adapter was not removed completely.
The best option would be a clean installation of the drivers for the Intel® Dual Band Wireless-AC 7260. Here is a suggestion of how you can do it
1. Download and save the latest driver: Intel® PROSet/Wireless Software and Drivers for Windows® 10 version: 18.40.0. *Note, this version is for the PROSet Package, however, the driver version for the adapter may vary. Make sure to take a look at the "Detailed Information" to learn more about it.
2. Go to Control Panel, Programs and Features and Uninstall "Intel® PROSet/Wireless Software", if it is installed. When prompted, choose the option to "Discard settings".
3. In Control Panel, Device Manager, Network Adapters, right click on the Intel® Dual Band Wireless-AC 7260 and Uninstall it. Make sure you mark the option to "Delete the driver software for this device".
4. Reboot the PC or scan for hardware changes, check device manager and if an older driver is detected and installed, repeat the actions to uninstall and delete it as well. Repeat this process until the OS does not allow deleting the driver, or until the controller shows as Unknown Device.
5. Reboot or scan for hardware changes, then uninstall and delete any older driver versions as you did for the Wireless adapter.
6. Install the Intel® Wireless driver. During the first steps of PROSet/Wireless installation, make sure to customize the installation and install all the 3 driver components as they improve WiDi functionality.
It is recommended also to consult with the motherboard manufacturer for compatibilty. With that being said, it is important to know that Intel does not support Integration which is when the original wireless adapter is replaced by another one. Please check this information for more details about it. Regulatory Information Regarding Hardware Installation or Upgrade.
As for the 5GHz, the router also must be compatible and properly configured so your wireless adapter can see it. Creating different SSIDs to tell 2.4GHz from 5GHz is an option. Here is some recommendation:
1. Go to Control Panel >> Device Manager >> Wireless Adapter and select the adapter and right click on it.
2. From the dialog box that shows, select the Adavanced Tab.
3. From the options available, find the HT Mode and change it to VHT mode as this mode is for 802.11ac compatibility.
4. Check the value of Transmit Power and make sure it's set to 5. Highest.