NPM: Default Site Showing Instead of App — Fix

The Problem

Visiting your domain shows the Nginx Proxy Manager default “Congratulations” page or a generic Nginx 404 page, instead of your actual application. The proxy host appears correctly configured in the NPM admin panel.

The Cause

NPM routes based on the Host header in the HTTP request. The default page appears when:

1. DNS points to the server but doesn’t match any proxy host — the domain in the browser must exactly match the “Domain Names” field in the proxy host
2. Cloudflare proxy is stripping the Host header — the orange cloud can interfere
3. Wildcard vs exact domain mismatch — app.example.com doesn’t match *.example.com unless configured
4. Port conflict — another service is binding port 80/443 before NPM

The Fix

Method 1: Verify Domain Name Match

In NPM admin → Proxy Hosts → Edit the host:

• The “Domain Names” field must exactly match what you type in the browser
• app.example.com and www.app.example.com are different — add both if needed
• Check for trailing spaces or invisible characters

Method 2: Verify DNS Resolution

# Check what IP the domain resolves to
dig +short app.example.com

# Should return YOUR server's public IP

If it returns a Cloudflare IP (104.x.x.x or 172.x.x.x), DNS is going through Cloudflare’s proxy. Either:

• Set the DNS record to “DNS only” (gray cloud) in Cloudflare
• Or keep the orange cloud but ensure the proxy host in NPM handles it correctly

Method 3: Check for Port Conflicts

# Check what's using ports 80 and 443
sudo ss -tlnp | grep ':80\|:443'

If Apache, another Nginx, or any other service is binding these ports, NPM can’t receive traffic. Stop the conflicting service:

sudo systemctl stop apache2
sudo systemctl disable apache2

Method 4: Check NPM Logs

docker logs nginx-proxy-manager 2>&1 | tail -50

Look for errors related to the specific proxy host or SSL certificate issues that might prevent routing.

Prevention

• Test with curl -H "Host: app.example.com" http://your-server-ip to verify NPM routes correctly before configuring DNS
• Keep domain names consistent — use exactly the domain your DNS points to
• Don’t run other web servers on port 80/443 alongside NPM

Related

• How to Self-Host Nginx Proxy Manager
• Nginx Proxy Manager vs Caddy
• Docker Networking