diff --git a/core/modules/menu_link_content/src/Entity/MenuLinkContent.php b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
index 7ab8a8e..4e2b513 100644
--- a/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
+++ b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
@@ -378,4 +378,29 @@ public function setRequiresRediscovery($rediscovery) {
     return $this;
   }
 
+  /**
+   * Disallow translation of internal links, and add a validation to
+   * avoid changing an internal to an external link and vice versa.
+   */
+  public function setTranslationConstraints() {
+    if (!$this->link->isEmpty()) {
+      // If the source link is internal we don't allow the translation.
+      $link_definition = $this->getFieldDefinition('link');
+
+      if (!$this->getUrlObject()->isExternal()) {
+        $link_definition->setTranslatable(FALSE);
+        // If a link is external we cannot use a internal one.
+        $link_definition->setSetting('link_type', LinkItemInterface::LINK_INTERNAL);
+      }
+      else {
+        $link_definition->setSetting('link_type', LinkItemInterface::LINK_EXTERNAL);
+      }
+      $item_definition = $link_definition->getItemDefinition();
+      $item_definition->addConstraint('LinkType');
+      $link_definition->setItemDefinition($item_definition);
+
+      $this->fieldDefinitions['link'] = $link_definition;
+    }
+  }
+  
 }
diff --git a/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php b/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
index ed372a9..9b67bc1 100644
--- a/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
+++ b/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
@@ -73,6 +73,7 @@ public function form(array $form, FormStateInterface $form_state) {
     $form = parent::form($form, $form_state);
 
     $default = $this->entity->getMenuName() . ':' . $this->entity->getParentId();
+    $this->entity->setTranslationConstraints();
     $id = $this->entity->isNew() ? '' : $this->entity->getPluginId();
     $form['menu_parent'] = $this->menuParentSelector->parentSelectElement($default, $id);
     $form['menu_parent']['#weight'] = 10;