diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0362ccf..1b106c3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -25,6 +25,21 @@ deploy_to_sinbad2:
     - echo "Levantando contenedores con Docker Compose..."
     - ssh $REMOTE_USER@$SSH_HOST "
         cd ~/deploy_$APP_NAME &&
+        echo 'Comprobando puertos en uso...' &&
+        docker ps --format '{{.ID}} {{.Ports}}' | grep -E '0.0.0.0:$FRONTEND_PORT->|0.0.0.0:$BACKEND_PORT->' || true &&
+        CONFLICT_FRONT=\$(docker ps -q --filter publish=$FRONTEND_PORT) &&
+        if [ ! -z \"\$CONFLICT_FRONT\" ]; then
+          echo \"Liberando puerto frontend $FRONTEND_PORT (contenedores: \$CONFLICT_FRONT)\" &&
+          docker stop \$CONFLICT_FRONT &&
+          docker rm \$CONFLICT_FRONT;
+        fi &&
+        CONFLICT_BACK=\$(docker ps -q --filter publish=$BACKEND_PORT) &&
+        if [ ! -z \"\$CONFLICT_BACK\" ]; then
+          echo \"Liberando puerto backend $BACKEND_PORT (contenedores: \$CONFLICT_BACK)\" &&
+          docker stop \$CONFLICT_BACK &&
+          docker rm \$CONFLICT_BACK;
+        fi &&
+        export BACKEND_PORT=$BACKEND_PORT FRONTEND_PORT=$FRONTEND_PORT ALLOWED_ORIGINS=\"http://sinbad2.ujaen.es,http://sinbad2.ujaen.es:$FRONTEND_PORT\" &&
         docker compose down --remove-orphans &&
         docker compose build --no-cache frontend backend &&
         docker compose up -d
diff --git a/docker-compose.yml b/docker-compose.yml
index c860b23..c6d0941 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -6,13 +6,13 @@ services:
       - ./backend/.env
     environment:
       DATABASE_URL: postgresql+psycopg://genexamenes:genexamenes@db:5432/genexamenes
-      # Sobrescribe backend/.env con el puerto actual del frontend.
-      ALLOWED_ORIGINS: http://sinbad2.ujaen.es,http://sinbad2.ujaen.es:8075
+      # Sobrescribe backend/.env con el origen público del frontend en despliegue.
+      ALLOWED_ORIGINS: ${ALLOWED_ORIGINS:-http://sinbad2.ujaen.es,http://sinbad2.ujaen.es:8075}
       LLM_BASE_URL: 
       LLM_MODEL: qwen3.5:35b
       LLM_TIMEOUT_SECONDS: "180"
     ports:
-      - "8074:8074"
+      - "${BACKEND_PORT:-8074}:8074"
     depends_on:
       db:
         condition: service_healthy
@@ -27,7 +27,7 @@ services:
         VITE_API_URL: ${VITE_API_URL:-http://sinbad2.ujaen.es:8074}
         VITE_GOOGLE_CLIENT_ID: ${VITE_GOOGLE_CLIENT_ID:-}
     ports:
-      - "8075:80"
+      - "${FRONTEND_PORT:-8075}:80"
     depends_on:
       - backend
     restart: unless-stopped