diff --git a/src/www/services_dhcpv6_edit.php b/src/www/services_dhcpv6_edit.php
index 362fc62fa..8e3d33b09 100644
--- a/src/www/services_dhcpv6_edit.php
+++ b/src/www/services_dhcpv6_edit.php
@@ -122,6 +122,12 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
             }
         }
 
+        // set 'domain' to first entry of 'domainsearchlist'
+        // (used only for DNS registration)
+        if (!empty($pconfig['domainsearchlist'])) {
+            $mapent['domain'] = $domain_array[0];
+        }
+
         if (isset($id)) {
             $config['dhcpdv6'][$if]['staticmap'][$id] = $mapent;
         } else {
@@ -210,7 +216,9 @@ include("head.inc");
                     <td>
                       <input name="domainsearchlist" type="text" value="<?=$pconfig['domainsearchlist'];?>" />
                       <div class="hidden" data-for="help_for_domainsearchlist">
-                        <?=gettext("The default is to use the domain name of this system as the domain search list option provided by DHCPv6. You may optionally specify one or multiple domain(s) here. Use the semicolon character as separator.");?>
+                        <?=gettext("If you want to use a custom domain search list for this host, you may optionally specify one or multiple domain(s) here. " .
+                        "Use the semicolon character as separator. The first domain in this list will also be used for DNS registration of this host (if enabled). " .
+                        "(If empty, the first domain in the interface's domain search list will be used. If this is empty, too, the system domain will be used.)");?>
                       </div>
                     </td>
                   </tr>