diff --git a/docker/nginx/nginx.conf b/docker/nginx/nginx.conf
index 8cb01a58b..744e82315 100644
--- a/docker/nginx/nginx.conf
+++ b/docker/nginx/nginx.conf
@@ -18,16 +18,21 @@ http {
     resolver 127.0.0.11 valid=10s ipv6=off;
 
     # Upstream servers (using Docker service names)
+    # NOTE: add `resolve` so nginx re-resolves container IPs after restarts.
+    # Otherwise nginx may keep stale DNS results and proxy to the wrong container.
     upstream gateway {
-        server gateway:8001;
+        zone gateway 64k;
+        server gateway:8001 resolve;
     }
 
     upstream langgraph {
-        server langgraph:2024;
+        zone langgraph 64k;
+        server langgraph:2024 resolve;
     }
 
     upstream frontend {
-        server frontend:3000;
+        zone frontend 64k;
+        server frontend:3000 resolve;
     }
 
     # ── Main server (path-based routing) ─────────────────────────────────