diff --git a/ui/nginx.conf b/ui/nginx.conf
index 80723ea..f33052e 100644
--- a/ui/nginx.conf
+++ b/ui/nginx.conf
@@ -5,8 +5,8 @@ server {
     # Allow large request bodies (screenshots are base64 encoded)
     client_max_body_size 50M;
 
-    # Use Docker's internal DNS resolver — resolves upstream at request time, not startup
-    resolver 127.0.0.11 valid=30s;
+    # Use Docker's internal DNS resolver (disable IPv6 to prevent SERVFAIL)
+    resolver 127.0.0.11 ipv6=off valid=30s;
     set $backend http://master:9090;
 
     # Serve static files from the React build