diff --git a/modules/quant_api/src/EventSubscriber/QuantApi.php b/modules/quant_api/src/EventSubscriber/QuantApi.php
index 750fd424..9938f46e 100644
--- a/modules/quant_api/src/EventSubscriber/QuantApi.php
+++ b/modules/quant_api/src/EventSubscriber/QuantApi.php
@@ -263,8 +263,13 @@ public function onOutput(QuantEvent $event) {
     /** @var \DOMElement $node */
     foreach ($xpath->query('//iframe[contains(@src, "/media/oembed")]') as $node) {
       $oembed_url = $new_href = $node->getAttribute('src');
-      $oembed_item = new RouteItem(['route' => $oembed_url]);
-      $oembed_item->send();
+      // Only add if it's a relative URL to handle the case where the URL
+      // contains `/media/oembed` but is from another website.
+      if (str_starts_with($oembed_url, '/')) {
+        $oembed_item = new RouteItem(['route' => $oembed_url]);
+        $oembed_item->send();
+        $this->logger->notice("[route_item] $oembed_url");
+      }
     }
 
     // @todo Report on forms that need proxying (attachments.forms).
diff --git a/src/Seed.php b/src/Seed.php
index 6ea13498..d7daee31 100644
--- a/src/Seed.php
+++ b/src/Seed.php
@@ -639,17 +639,37 @@ public static function rewriteRelative($markup) {
     // Do not strip host domain unless configured.
     $strip = $config->get('host_domain_strip') ?: FALSE;
     if (!$strip) {
+      // Handle iframes even if `host_domain_strip` is disabled, so iframe
+      // renders correctly.
+      $markup = self::rewriteRelativeIframe($markup);
+
       return $markup;
     }
 
     // Strip the host domain from everywhere in the content including header
     // metadata such as canonical links.
-    $hostname = $config->get('host_domain') ?: $_SERVER['SERVER_NAME'];
-    $port = $_SERVER['SERVER_PORT'];
-    $markup = preg_replace("/(https?:\/\/)?{$hostname}(\:{$port})?/i", '', $markup);
+    $markup = Utility::stripLocalHost($markup);
 
-    // Edge case: Replace http://default when run via drush without base_url.
-    $markup = preg_replace("/http:\/\/default/i", '', $markup);
+    return $markup;
+  }
+
+  /**
+   * Replaces absolute iframe URLs with relative in markup.
+   *
+   * @param string $markup
+   *   The markup to search and rewire relative iframe paths for.
+   *
+   * @return string
+   *   Sanitized markup string.
+   */
+  public static function rewriteRelativeIframe($markup) {
+    $pattern = '/<iframe src="([^"]+)"/i';
+    if (preg_match_all($pattern, $markup, $matches)) {
+      foreach ($matches[1] as $url) {
+        $updated_url = Utility::stripLocalHost($url);
+        $markup = str_replace($url, $updated_url, $markup);
+      }
+    }
 
     return $markup;
   }
diff --git a/src/Utility.php b/src/Utility.php
index b4895ed6..2326143c 100644
--- a/src/Utility.php
+++ b/src/Utility.php
@@ -108,7 +108,7 @@ public static function getPathPrefix(string $langcode = NULL) : string {
    * @return string
    *   The relative canonical URL.
    */
-  public static function getCanonicalUrl($type, $id, $langcode) {
+  public static function getCanonicalUrl(string $type, int $id, string $langcode) : string {
     $options = ['absolute' => FALSE];
     if (!empty($langcode)) {
       $language = \Drupal::languageManager()->getLanguage($langcode);
@@ -119,6 +119,28 @@ public static function getCanonicalUrl($type, $id, $langcode) {
     return Url::fromRoute('entity.' . $type . '.canonical', [$type => $id], $options)->toString();
   }
 
+  /**
+   * Strip local host from text.
+   *
+   * @param string $text
+   *   The text.
+   *
+   * @return string
+   *   The text without local host.
+   */
+  public static function stripLocalHost(string $text) : string {
+
+    $config = \Drupal::config('quant.settings');
+    $hostname = $config->get('host_domain') ?: $_SERVER['SERVER_NAME'];
+    $port = $_SERVER['SERVER_PORT'];
+    $text = preg_replace("/(https?:\/\/)?{$hostname}(\:{$port})?/i", '', $text);
+
+    // Edge case: Replace http://default when run via drush without base_url.
+    $text = preg_replace("/http:\/\/default/i", '', $text);
+
+    return $text;
+  }
+
   /**
    * Checks if it's an external URL.
    *