diff --git a/ui/nginx.conf b/ui/nginx.conf
index a50c4c1..80723ea 100644
--- a/ui/nginx.conf
+++ b/ui/nginx.conf
@@ -5,6 +5,10 @@ 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;
+    set $backend http://master:9090;
+
     # Serve static files from the React build
     location / {
         root   /usr/share/nginx/html;
@@ -14,8 +18,8 @@ server {
 
     # Reverse proxy API requests to the Master backend container
     location /api/ {
-        proxy_pass http://master:9090;
-        
+        proxy_pass $backend;
+
         # Standard proxy headers
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;