nixpkgs/nixos/doc/manual/configuration/network-manager.xml

<section xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-networkmanager">

<title>NetworkManager</title>

<para>To facilitate network configuration, some desktop environments
use NetworkManager. You can enable NetworkManager by setting:

<programlisting>
networking.networkmanager.enable = true;
</programlisting>

some desktop managers (e.g., GNOME) enable NetworkManager
automatically for you.</para>

<para>All users that should have permission to change network settings must
belong to the <code>networkmanager</code> group:

<programlisting>
users.extraUsers.youruser.extraGroups = [ "networkmanager" ];
</programlisting>
</para>

<para>NetworkManager is controlled using either <command>nmcli</command> or
<command>nmtui</command> (curses-based terminal user interface). See their
manual pages for details on their usage. Some desktop environments (GNOME, KDE)
have their own configuration tools for NetworkManager. On XFCE, there is no
configuration tool for NetworkManager by default: by adding
<code>networkmanagerapplet</code> to the list of system packages, the graphical
applet will be installed and will launch automatically when XFCE is starting
(and will show in the status tray).</para>

<note><para><code>networking.networkmanager</code> and
<code>networking.wireless</code> (WPA Supplicant) cannot be enabled at the same
time: you can still connect to the wireless networks using
NetworkManager.</para></note>

</section>