diff --git a/esphome/components/web_server/__init__.py b/esphome/components/web_server/__init__.py
index e36b6a3bb3..0cdf10531d 100644
--- a/esphome/components/web_server/__init__.py
+++ b/esphome/components/web_server/__init__.py
@@ -339,6 +339,7 @@ async def to_code(config):
         cg.add_define("USE_WEBSERVER_GZIP")
 
     # Extract domains from CDN URLs for DNS whitelisting (used by captive_portal)
+    # This handles both default URLs (using CDN_HOST) and custom user URLs
     cdn_domains: set[str] = set()
     for url_key in (CONF_CSS_URL, CONF_JS_URL):
         url = config.get(url_key, "")