Troubleshooting:Service Troubleshooting

Service Troubleshooting

This guide covers troubleshooting for reverse proxy services.

Common Issues

Issue: 502 Bad Gateway

Causes:

• Service not running on Synology NAS

• 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

= 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

Issue: Service Not Loading

Causes:

• Wrong proxy_pass URL

• Missing headers

• Service requires specific path

Solutions:

• Check nginx error log: tail -f /var/log/nginx/error.log

• Verify service works directly: curl http://10.8.0.2:PORT

• Test with different proxy_pass formats

Issue: Connection Timeout

Causes:

• VPN tunnel down

• Service not accessible

• Firewall blocking

Solutions:

= Check VPN =
ip addr show tun0
ping 10.8.0.2

= Check routing =
ip route | grep 10.8.0.2

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

Diagnostic Commands

= Check service status =
systemctl status nginx

= Test nginx configuration =
nginx -t

= View error logs =
tail -f /var/log/nginx/error.log

= View access logs =
tail -f /var/log/nginx/access.log

= Check SSL certificates =
certbot certificates

= Test service directly =
curl -I https://service.jb-vpn.uk

Related Documentation

• [Adding Services](index.md) - Service configuration

• [System Overview](index.md) - System architecture