diff --git a/Makefile b/Makefile
index f216285..db271b8 100644
--- a/Makefile
+++ b/Makefile
@@ -511,6 +511,17 @@ release-docker: ## Build and push release Docker images
 pre-release-docker: ## Build and push pre-release Docker images
 	./publish-docker-prerelease.sh
 
+dev-release: ## Build and push custom dev release (usage: make dev-release NAME=issue38)
+	@if [ -z "$(NAME)" ]; then \
+		echo "$(RED)ERROR: NAME parameter is required!$(NC)"; \
+		echo "$(YELLOW)Usage: make dev-release NAME=<custom-name>$(NC)"; \
+		echo "$(YELLOW)Example: make dev-release NAME=issue38$(NC)"; \
+		echo "$(YELLOW)  This will create tags like: 0.3.1-dev-issue38$(NC)"; \
+		exit 1; \
+	fi
+	@echo "$(BLUE)Building custom dev release: $(NAME)$(NC)"
+	@./publish-docker-dev.sh $(NAME)
+
 #===============================================================================
 # DATABASE
 #===============================================================================
diff --git a/README.md b/README.md
index 9c2510b..6b566c0 100644
--- a/README.md
+++ b/README.md
@@ -120,14 +120,17 @@ docker compose up -d
 
 When running ExcaliDash behind Traefik, Nginx, or another reverse proxy, configure both containers so that API + WebSocket calls resolve correctly:
 
-- `FRONTEND_URL` (backend) must match the public URL that users hit (e.g. `https://excalidash.example.com`). This controls CORS and Socket.IO origin checks.
+- `FRONTEND_URL` (backend) must match the public URL that users hit (e.g. `https://excalidash.example.com`). This controls CORS and Socket.IO origin checks. **Supports multiple comma-separated URLs** for accessing from different addresses.
 - `BACKEND_URL` (frontend) tells the Nginx container how to reach the backend from inside Docker/Kubernetes. Override it if your reverse proxy exposes the backend under a different hostname.
 
 ```yaml
 # docker-compose.yml example
 backend:
   environment:
+    # Single URL
     - FRONTEND_URL=https://excalidash.example.com
+    # Or multiple URLs (comma-separated) for local + network access
+    # - FRONTEND_URL=http://localhost:6767,http://192.168.1.100:6767,http://nas.local:6767
 frontend:
   environment:
     # For standard Docker Compose (default)
diff --git a/VERSION b/VERSION
index 9e11b32..d15723f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.3.1
+0.3.2
diff --git a/backend/package-lock.json b/backend/package-lock.json
index c328369..77eb32a 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "backend",
-  "version": "0.3.0",
+  "version": "0.3.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "backend",
-      "version": "0.3.0",
+      "version": "0.3.2",
       "license": "ISC",
       "dependencies": {
         "@prisma/client": "^5.22.0",
diff --git a/backend/package.json b/backend/package.json
index f75a26c..bb277ae 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "backend",
-  "version": "0.3.1",
+  "version": "0.3.2",
   "description": "",
   "main": "index.js",
   "scripts": {
diff --git a/backend/src/__tests__/csrf-trust-proxy.test.ts b/backend/src/__tests__/csrf-trust-proxy.test.ts
new file mode 100644
index 0000000..beadca9
--- /dev/null
+++ b/backend/src/__tests__/csrf-trust-proxy.test.ts
@@ -0,0 +1,172 @@
+/**
+ * Issue #38: CSRF fails with multiple reverse proxies
+ *
+ * This test demonstrates how trust proxy settings affect CSRF validation
+ * when ExcaliDash is behind multiple proxy layers (e.g., Traefik, Synology NAS)
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import express from "express";
+import request from "supertest";
+import {
+  createCsrfToken,
+  validateCsrfToken,
+  getCsrfTokenHeader,
+} from "../security";
+
+// mock the getClientId function behavior
+const getClientIdFromRequest = (req: express.Request): string => {
+  const ip = req.ip || req.connection.remoteAddress || "unknown";
+  const userAgent = req.headers["user-agent"] || "unknown";
+  return `${ip}:${userAgent}`.slice(0, 256);
+};
+
+describe("Issue #38: CSRF with trust proxy settings", () => {
+  let app: express.Application;
+
+  beforeEach(() => {
+    app = express();
+    app.use(express.json());
+  });
+
+  it("demonstrates the trust proxy issue with multiple proxies", async () => {
+    // ext proxy -> frontend nginx -> backend
+    // X-Forwarded-For: 203.0.113.42 (client), 10.0.0.5 (external proxy), 172.17.0.3 (frontend nginx)
+
+    // With trust proxy: 1 (current setting)
+    const app1 = express();
+    app1.set("trust proxy", 1);
+    app1.use(express.json());
+
+    app1.get("/test-ip", (req, res) => {
+      res.json({
+        ip: req.ip,
+        clientId: getClientIdFromRequest(req),
+      });
+    });
+
+    // Simulate request through multiple proxies
+    const response1 = await request(app1)
+      .get("/test-ip")
+      .set("X-Forwarded-For", "203.0.113.42, 10.0.0.5, 172.17.0.3")
+      .set("User-Agent", "Mozilla/5.0 Test");
+
+    // With trust proxy: 1 in supertest (no real socket), Express takes the last IP
+    // In production with a real connection, behavior differs - the key point is it's NOT the client IP
+    expect(response1.body.ip).toBe("172.17.0.3");
+    console.log(
+      "trust proxy: 1 → IP:",
+      response1.body.ip,
+      "(not the real client IP)",
+    );
+
+    // With trust proxy: true
+    const app2 = express();
+    app2.set("trust proxy", true);
+    app2.use(express.json());
+
+    app2.get("/test-ip", (req, res) => {
+      res.json({
+        ip: req.ip,
+        clientId: getClientIdFromRequest(req),
+      });
+    });
+
+    const response2 = await request(app2)
+      .get("/test-ip")
+      .set("X-Forwarded-For", "203.0.113.42, 10.0.0.5, 172.17.0.3")
+      .set("User-Agent", "Mozilla/5.0 Test");
+
+    // With trust proxy: true, Express takes leftmost IP
+    expect(response2.body.ip).toBe("203.0.113.42");
+    console.log(
+      "trust proxy: true → IP:",
+      response2.body.ip,
+      "(real client IP - CORRECT)",
+    );
+  });
+
+  it("simulates CSRF failure scenario from issue #38", async () => {
+    const userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64)";
+
+    // Request 1: Fetch CSRF token
+    // X-Forwarded-For shows: client, external-proxy-1, frontend-nginx
+    const clientIp1 = "203.0.113.42";
+    const externalProxyIp1 = "10.0.0.5"; // External proxy IP on first request
+
+    // With trust proxy: 1, Express sees the external proxy IP
+    const clientId1 = `${externalProxyIp1}:${userAgent}`;
+    const token = createCsrfToken(clientId1);
+
+    console.log(
+      "  X-Forwarded-For:",
+      `${clientIp1}, ${externalProxyIp1}, 172.17.0.3`,
+    );
+    console.log("  Express sees IP:", externalProxyIp1);
+    console.log("  ClientId:", clientId1.slice(0, 50) + "...");
+
+    // Request 2: Try to create drawing with token
+    // External proxy IP might differ slightly
+    const externalProxyIp2 = "10.0.0.6";
+
+    const clientId2 = `${externalProxyIp2}:${userAgent}`;
+
+    console.log(
+      "  X-Forwarded-For:",
+      `${clientIp1}, ${externalProxyIp2}, 172.17.0.3`,
+    );
+    console.log("  Express sees IP:", externalProxyIp2);
+    console.log("  ClientId:", clientId2.slice(0, 50) + "...");
+
+    // CSRF validation fails because clientId changed
+    const isValid = validateCsrfToken(clientId2, token);
+
+    expect(isValid).toBe(false);
+    console.log("   Expected:", clientId1.slice(0, 50) + "...");
+    console.log("   Got:", clientId2.slice(0, 50) + "...");
+  });
+
+  it("shows the fix works with trust proxy: true", async () => {
+    const userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64)";
+    const realClientIp = "203.0.113.42";
+
+    const clientId1 = `${realClientIp}:${userAgent}`;
+    const token = createCsrfToken(clientId1);
+
+    console.log("  X-Forwarded-For:", `${realClientIp}, 10.0.0.5, 172.17.0.3`);
+    console.log("  Express sees IP:", realClientIp);
+
+    // Request 2: Use token (even if middle proxy IPs differ)
+    const clientId2 = `${realClientIp}:${userAgent}`;
+
+    console.log("Create drawing");
+    console.log("X-Forwarded-For:", `${realClientIp}, 10.0.0.6, 172.17.0.3`);
+    console.log("Express sees IP:", realClientIp, "(same!)");
+
+    const isValid = validateCsrfToken(clientId2, token);
+
+    expect(isValid).toBe(true);
+    console.log("\nCSRF Validation: SUCCESS");
+  });
+
+  it("demonstrates the Synology NAS scenario from issue #38", async () => {
+    const app = express();
+    app.set("trust proxy", 1);
+    app.use(express.json());
+
+    let seenIp: string | undefined;
+    app.get("/test", (req, res) => {
+      seenIp = req.ip;
+      res.json({ ip: req.ip });
+    });
+
+    // Client -> Synology (192.168.1.x) -> Docker frontend (192.168.11.x) -> Backend
+    // In supertest without real socket, trust proxy: 1 returns last IP
+    // Key point: it's NOT the real client IP (192.168.0.100)
+    await request(app)
+      .get("/test")
+      .set("X-Forwarded-For", "192.168.0.100, 192.168.1.4, 192.168.11.166");
+    console.log("  With trust proxy: 1, Express sees:", seenIp);
+    expect(seenIp).toBe("192.168.11.166"); // Not the real client IP
+  });
+});
diff --git a/backend/src/index.ts b/backend/src/index.ts
index 6de2da1..506646e 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -148,8 +148,21 @@ const app = express();
 
 // Trust proxy headers (X-Forwarded-For, X-Real-IP) from nginx
 // Required for correct client IP detection when running behind a reverse proxy
-// This fixes CSRF token validation failures in Docker/K8s environments
-app.set("trust proxy", 1);
+// Fix for issue #38: Use 'true' to handle multiple proxy layers (e.g., Traefik, Synology NAS)
+// This ensures Express extracts the real client IP from the leftmost X-Forwarded-For value
+const trustProxyConfig = process.env.TRUST_PROXY || "true";
+const trustProxyValue = trustProxyConfig === "true"
+  ? true
+  : trustProxyConfig === "false"
+  ? false
+  : parseInt(trustProxyConfig, 10) || 1;
+app.set("trust proxy", trustProxyValue);
+
+if (trustProxyValue === true) {
+  console.log("[config] trust proxy: enabled (handles multiple proxy layers)");
+} else {
+  console.log(`[config] trust proxy: ${trustProxyValue}`);
+}
 
 const httpServer = createServer(app);
 const io = new Server(httpServer, {
@@ -346,9 +359,24 @@ app.use((req, res, next) => {
 const getClientId = (req: express.Request): string => {
   const ip = req.ip || req.connection.remoteAddress || "unknown";
   const userAgent = req.headers["user-agent"] || "unknown";
-  // Create a simple hash for client identification
-  // In production, you might use a session ID instead
-  return `${ip}:${userAgent}`.slice(0, 256);
+  const clientId = `${ip}:${userAgent}`.slice(0, 256);
+
+  // Debug logging for CSRF troubleshooting (issue #38)
+  if (process.env.DEBUG_CSRF === "true") {
+    console.log("[CSRF DEBUG] getClientId", {
+      method: req.method,
+      path: req.path,
+      ip,
+      remoteAddress: req.connection.remoteAddress,
+      "x-forwarded-for": req.headers["x-forwarded-for"],
+      "x-real-ip": req.headers["x-real-ip"],
+      userAgent: userAgent.slice(0, 100),
+      clientIdPreview: clientId.slice(0, 60) + "...",
+      trustProxySetting: req.app.get("trust proxy"),
+    });
+  }
+
+  return clientId;
 };
 
 // Rate limiter specifically for CSRF token generation to prevent store exhaustion
diff --git a/backend/src/security.ts b/backend/src/security.ts
index 8696b11..3cb0771 100644
--- a/backend/src/security.ts
+++ b/backend/src/security.ts
@@ -583,8 +583,12 @@ const getCsrfSecret = (): Buffer => {
   cachedCsrfSecret = crypto.randomBytes(32);
   const envLabel = process.env.NODE_ENV ? ` (${process.env.NODE_ENV})` : "";
   console.warn(
-    `[security] CSRF_SECRET is not set${envLabel}. Using an ephemeral per-process secret. ` +
-      "For horizontal scaling (k8s), set CSRF_SECRET to the same value on all instances."
+    `[SECURITY WARNING] CSRF_SECRET is not set${envLabel}.\n` +
+      `Using an ephemeral per-process secret.\n` +
+      `  - Tokens will expire on container restart\n` +
+      `  - Horizontal scaling (k8s) will NOT work\n` +
+      `  - Generate a secret: openssl rand -base64 32\n` +
+      `  - Set environment variable: CSRF_SECRET=<generated-secret>`
   );
   return cachedCsrfSecret;
 };
diff --git a/frontend/package.json b/frontend/package.json
index c1f8eca..da2d6be 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "frontend",
   "private": true,
-  "version": "0.3.1",
+  "version": "0.3.2",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/publish-docker-dev.sh b/publish-docker-dev.sh
new file mode 100755
index 0000000..679d8a9
--- /dev/null
+++ b/publish-docker-dev.sh
@@ -0,0 +1,109 @@
+#!/bin/bash
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Custom name is required
+CUSTOM_NAME=$1
+
+if [ -z "$CUSTOM_NAME" ]; then
+    echo -e "${RED}ERROR: Custom name is required!${NC}"
+    echo -e "${YELLOW}Usage: $0 <custom-name>${NC}"
+    echo -e "${YELLOW}Example: $0 issue38${NC}"
+    echo -e "${YELLOW}  This will create tags like: 0.3.1-dev-issue38${NC}"
+    exit 1
+fi
+
+# Configuration
+DOCKER_USERNAME="zimengxiong"
+IMAGE_NAME="excalidash"
+BASE_VERSION=$(node -e "try { console.log(require('fs').readFileSync('VERSION', 'utf8').trim()) } catch { console.log('0.0.0') }")
+VERSION="${BASE_VERSION}-dev-${CUSTOM_NAME}"
+CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+
+echo -e "${BLUE}===========================================${NC}"
+echo -e "${BLUE}ExcaliDash Custom Dev Release${NC}"
+echo -e "${BLUE}===========================================${NC}"
+echo ""
+echo -e "${YELLOW}Branch:       ${CURRENT_BRANCH}${NC}"
+echo -e "${YELLOW}Base version: ${BASE_VERSION}${NC}"
+echo -e "${YELLOW}Custom name:  ${CUSTOM_NAME}${NC}"
+echo -e "${YELLOW}Full tag:     ${VERSION}${NC}"
+echo ""
+echo -e "${YELLOW}This will publish images with tag: ${VERSION}${NC}"
+echo -e "${YELLOW}Dev images will NOT update 'latest' or 'dev' tags${NC}"
+echo ""
+
+# Confirm before proceeding
+read -p "Continue? (y/N) " -n 1 -r
+echo
+if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+    echo -e "${RED}Aborted.${NC}"
+    exit 1
+fi
+
+# Check if logged in to Docker Hub
+echo -e "${YELLOW}Checking Docker Hub authentication...${NC}"
+if ! docker info | grep -q "Username: $DOCKER_USERNAME"; then
+    echo -e "${YELLOW}Not logged in. Please login to Docker Hub:${NC}"
+    docker login
+else
+    echo -e "${GREEN}✓ Already logged in as $DOCKER_USERNAME${NC}"
+fi
+
+# Create buildx builder if it doesn't exist
+echo -e "${YELLOW}Setting up buildx builder...${NC}"
+if ! docker buildx inspect excalidash-builder > /dev/null 2>&1; then
+    echo -e "${YELLOW}Creating new buildx builder...${NC}"
+    docker buildx create --name excalidash-builder --use --bootstrap
+else
+    echo -e "${GREEN}✓ Using existing buildx builder${NC}"
+    docker buildx use excalidash-builder
+fi
+
+# Build and push backend image
+echo ""
+echo -e "${BLUE}Building and pushing backend image...${NC}"
+docker buildx build \
+    --platform linux/amd64,linux/arm64 \
+    --tag $DOCKER_USERNAME/$IMAGE_NAME-backend:$VERSION \
+    --file backend/Dockerfile \
+    --push \
+    backend/
+
+echo -e "${GREEN}✓ Backend image pushed successfully${NC}"
+
+# Build and push frontend image
+echo ""
+echo -e "${BLUE}Building and pushing frontend image...${NC}"
+docker buildx build \
+    --platform linux/amd64,linux/arm64 \
+    --tag $DOCKER_USERNAME/$IMAGE_NAME-frontend:$VERSION \
+    --build-arg VITE_APP_VERSION=$VERSION \
+    --file frontend/Dockerfile \
+    --push \
+    .
+
+echo -e "${GREEN}✓ Frontend image pushed successfully${NC}"
+
+echo ""
+echo -e "${BLUE}===========================================${NC}"
+echo -e "${GREEN}✓ Custom dev images published!${NC}"
+echo -e "${BLUE}===========================================${NC}"
+echo ""
+echo -e "${YELLOW}Images published:${NC}"
+echo -e "  • $DOCKER_USERNAME/$IMAGE_NAME-backend:$VERSION"
+echo -e "  • $DOCKER_USERNAME/$IMAGE_NAME-frontend:$VERSION"
+echo ""
+echo -e "${YELLOW}To use these images in docker-compose:${NC}"
+echo -e "${BLUE}  services:"
+echo -e "    backend:"
+echo -e "      image: $DOCKER_USERNAME/$IMAGE_NAME-backend:$VERSION"
+echo -e "    frontend:"
+echo -e "      image: $DOCKER_USERNAME/$IMAGE_NAME-frontend:$VERSION${NC}"
+echo ""