Troubleshooting:Service Troubleshooting

This guide covers troubleshooting for reverse proxy services on the VPS. Public HTTPS is handled by Caddy (/etc/caddy/Caddyfile).

Common Issues

Issue: 502 Bad Gateway

Causes:

• Backend not running (Docker on VPS or service on NAS)

• Caddy misconfigured or not reloaded after Caddyfile change

• Wrong port number

• Service not accessible via VPN

Solutions:

# Test from VPS to NAS
ping 10.8.0.2
curl http://10.8.0.2:PORT_NUMBER

# Test VPS-local Docker service
curl -sI http://127.0.0.1:PORT_NUMBER

# Check Caddy logs
journalctl -u caddy -n 50

# Check if service is listening (from Synology NAS or via SSH)
netstat -tlnp | grep PORT_NUMBER

Issue: SSL Certificate Failed

Causes:

• DNS not pointing to VPS

• Port 80 blocked

• Rate limiting from Let's Encrypt

Solutions:

# Check DNS
nslookup newservice.jb-vpn.uk

# Verify port 80 is open
curl -I http://newservice.jb-vpn.uk

# Check firewall
sudo iptables -L -n -v | grep 80

# Validate Caddy config
caddy validate --config /etc/caddy/Caddyfile

Issue: Service Not Loading

Causes:

• Wrong upstream URL in Caddyfile

• Missing proxy headers

• Service requires specific path

Solutions:

• Check Caddy: journalctl -u caddy -n 50

• Verify backend directly: curl http://127.0.0.1:PORT (VPS) or curl http://10.8.0.2:PORT (NAS via VPN)

• Validate and reload: caddy validate --config /etc/caddy/Caddyfile && systemctl reload caddy

Issue: Connection Timeout

Causes:

• VPN tunnel down

• Service not accessible

• Firewall blocking

Solutions:

# Check VPN
ip addr show tun0
ping 10.8.0.2
cat /var/log/openvpn-status.log

# Check routing
ip route | grep 10.8.0.0

# Test connectivity
curl -v http://10.8.0.2:PORT_NUMBER

Diagnostic Commands

# Caddy
caddy validate --config /etc/caddy/Caddyfile
systemctl status caddy
systemctl reload caddy
journalctl -u caddy -n 50

# OpenVPN (for NAS-backed services)
systemctl status openvpn-server@server.service
ip addr show tun0
cat /var/log/openvpn-status.log

# Test public endpoint
curl -I https://service.jb-vpn.uk

# Docker stacks on VPS
cd /var/www/wiki.jb && docker compose ps

Service-specific guides

• Plex: Troubleshooting:Plex Troubleshooting — auth, custom access URLs, Caddy pitfalls

• Nginx (legacy): Troubleshooting:Nginx Troubleshooting — host/WebApp internal nginx only

Related Documentation

• Services:Current Services — service inventory

• System:Components — Caddy, VPN, Docker components