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>
<xref linkend="opt-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>
<link linkend="opt-users.users._name__.extraGroups">users.users.alice.extraGroups</link> = [ "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>