diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index 58ab7207f53..012c2e4f992 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -484,6 +484,14 @@
        (<literal>citrix_workspace</literal>).
      </para>
    </listitem>
+   <listitem>
+    <para>
+      The <option>networking.useDHCP</option> option is unsupported in combination with
+      <option>networking.useNetworkd</option> in anticipation of defaulting to it by default.
+      It has to be set to <literal>false</literal> and enabled per
+      interface with <option>networking.interfaces.&lt;name&gt;.useDHCP = true;</option>
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 
diff --git a/nixos/modules/tasks/network-interfaces.nix b/nixos/modules/tasks/network-interfaces.nix
index 5bf7b0d227f..834ce758410 100644
--- a/nixos/modules/tasks/network-interfaces.nix
+++ b/nixos/modules/tasks/network-interfaces.nix
@@ -903,6 +903,11 @@ in
         Whether to use DHCP to obtain an IP address and other
         configuration for all network interfaces that are not manually
         configured.
+
+        Using this option is highly discouraged and also incompatible with
+        <option>networking.useNetworkd</option>. Please use
+        <option>networking.interfaces.&lt;name&gt;.useDHCP</option> instead
+        and set this to false.
       '';
     };