Got it, let's walk through this step by step— I’ve set up exactly this kind of QNAP + Docker + custom domain setup a handful of times, so I know the ropes. Here’s how to get your Node.js app accessible from the outside, both via your myqnapcloud domain and your custom domain:

Since you have a static public IP, start here to let external traffic reach your NAS:

• Log into your home router’s admin panel (usually via something like 192.168.1.1). Find the Port Forwarding or Virtual Servers section.
• Add two rules:
  • Forward public port 80 (HTTP) to your NAS’s local IP and port 80
  • Forward public port 443 (HTTPS) to your NAS’s local IP and port 443
• Head to your QNAP’s Control Panel > Security > Firewall and add inbound rules to allow traffic on ports 80 and 443 from any source (or restrict to specific IPs if you want extra security).

QNAP has built-in reverse proxy tools that make mapping domains to your Docker app straightforward:

• Go to Control Panel > Network & File Services > Web Server > Reverse Proxy (some QNAP versions might have this under "Application Services").
• Add your first rule for the myqnapcloud domain:
  • Source: Select HTTPS (always prefer HTTPS over HTTP), enter my-server.myqnapcloud.com as the hostname, set port to 443, and if you want a subpath like /my-app, enter that in the "Path" field.
  • Destination: Select HTTP (unless your Node.js app uses HTTPS internally), enter your NAS’s local IP (or localhost if your container is on the same network), and input your <local-port> (the one you use to access the app locally).
  • Check the WebSocket box if your Node.js app uses real-time features (like chat or live updates)— this is easy to miss but critical for those use cases.
• Save the rule. You can test this right away by accessing https://my-server.myqnapcloud.com/my-app from a device not on your local WiFi.

To map your own domain to the app:

• Go to your domain registrar’s website (where you bought your custom domain) and navigate to DNS settings.
• Add an A Record: Point your domain (e.g., my-domain.com) or subdomain (e.g., my-app.my-domain.com) to your NAS’s static public IP. Note: DNS changes can take 10 minutes to a few hours to propagate.
• Back in QNAP’s Reverse Proxy settings, add a second rule:
  • Source: Again use HTTPS, enter your custom domain/subdomain as the hostname, port 443.
  • Destination: Same as before— NAS local IP and <local-port>.
• (Critical) Get an SSL certificate for your custom domain: Go to Control Panel > Security > SSL Certificates, click Add > Let’s Encrypt, enter your custom domain, and follow the prompts. This removes the "unsecure" browser warning when accessing your app.

Make sure your Node.js container is configured to accept external traffic:

• Open Container Station, find your Node.js app, and go to Settings > Network.
• Confirm your port mapping is correct: The container’s internal port (e.g., 3000, where your Node.js app is listening) should be mapped to your NAS’s <local-port>.
• If you’re using QNAP’s default bridge network, ensure the container is reachable from the NAS (you can test this by pinging the container’s IP from the NAS’s terminal if needed).

• Use a mobile device on cellular data (not your home WiFi) to visit both https://my-server.myqnapcloud.com/my-app and your custom domain once DNS propagates.
• If you run into issues, check:
  • Router port forwarding rules are active
  • QNAP firewall isn’t blocking traffic
  • Reverse proxy rules have the correct ports and hostnames
  • Your Node.js app is running and listening on the correct internal port

内容的提问来源于stack exchange，提问作者Łukasz Ostrowski