diff --git a/src/opnsense/mvc/app/models/OPNsense/Kea/KeaDhcpv6.php b/src/opnsense/mvc/app/models/OPNsense/Kea/KeaDhcpv6.php
index 173bb7efc2..dad955106e 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Kea/KeaDhcpv6.php
+++ b/src/opnsense/mvc/app/models/OPNsense/Kea/KeaDhcpv6.php
@@ -91,6 +91,31 @@ class KeaDhcpv6 extends BaseModel
                 }
             }
         }
+        // validate changed pd_pools
+        foreach ($this->pd_pools->pd_pool->iterateItems() as $pool) {
+            if (!$validateFullModel && !$pool->isFieldChanged()) {
+                continue;
+            }
+            $key = $pool->__reference;
+            if ($pool->prefix_len->getValue() >= $pool->delegated_len->getValue()) {
+                $messages->appendMessage(new Message(gettext("Delegated length must be longer than or equal to prefix length"), $key . ".delegated_len"));
+            }
+            $subnet = $pool->prefix->getValue() . "/" . $pool->prefix_len->getValue();
+            $trange = Util::cidrToRange($subnet);
+            if (!Util::isSubnetStrict($subnet)) {
+                $messages->appendMessage(new Message(gettext("Invalid Pool boundaries, offered address is not the first address in the prefix."), $key . ".prefix"));
+            }
+            foreach ($this->pd_pools->pd_pool->iterateItems() as $tmppool) {
+                if ($key === $tmppool->__reference) {
+                    continue;
+                }
+                $osubnet = $tmppool->prefix->getValue() . "/" . $tmppool->prefix_len->getValue();
+                $orange = Util::cidrToRange($osubnet);
+                if (Util::isIPInCIDR($orange[0], $subnet) || Util::isIPInCIDR($trange[0], $osubnet)) {
+                    $messages->appendMessage(new Message(gettext("Pool overlaps with an existing one."), $key . ".prefix"));
+                }
+            }
+        }
 
         return $messages;
     }