diff --git a/nginx/nginx.conf b/nginx/nginx.conf
index 12930ca..fecb73e 100644
--- a/nginx/nginx.conf
+++ b/nginx/nginx.conf
@@ -5,18 +5,15 @@ events {
 http {
     client_max_body_size 10m;
 
-    upstream backend {
-        server backend:8000;
-    }
-
-    upstream frontend {
-        server frontend:5173;
-    }
-
     server {
         listen 80;
         server_name localhost;
 
+        # Use Docker's internal DNS so nginx re-resolves after container restarts
+        resolver 127.0.0.11 valid=5s;
+        set $backend_upstream http://backend:8000;
+        set $frontend_upstream http://frontend:5173;
+
         # OTA firmware files — allow browser (esptool-js) to fetch .bin files directly
         location /ota/ {
             root /srv;
@@ -31,7 +28,7 @@ http {
 
         # API requests → FastAPI backend
         location /api/ {
-            proxy_pass http://backend;
+            proxy_pass $backend_upstream;
             proxy_set_header Host $host;
             proxy_set_header X-Real-IP $remote_addr;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
@@ -40,7 +37,7 @@ http {
 
         # WebSocket support for MQTT live data
         location /api/mqtt/ws {
-            proxy_pass http://backend;
+            proxy_pass $backend_upstream;
             proxy_http_version 1.1;
             proxy_set_header Upgrade $http_upgrade;
             proxy_set_header Connection "upgrade";
@@ -49,7 +46,7 @@ http {
 
         # Everything else → React frontend (Vite dev server)
         location / {
-            proxy_pass http://frontend;
+            proxy_pass $frontend_upstream;
             proxy_set_header Host $host;
             proxy_set_header X-Real-IP $remote_addr;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;