nstallation of the iwlwifi driver for Intel wireless on Debian is simplicity itself. There's a Debian Wifi Wiki which explains the process along with a list of supported wireless hardware. First, ensure non-free is added to ATP sources.list, to enable downloads.
You can check this with:
# cat /etc/apt/sources.list
Update package list
# apt update
Install iwlwifi firmware
# apt-get install firmware-iwlwifi
Insert wifi module
# modprobe -r iwlwifi ; modprobe iwlwifi
With wifi driver is installed, next, connect to a wifi source. Open Networ-Manager, select your router connection, and enter password.
Wireless connection is complete.