Editing Troubleshooting:Service Troubleshooting

This guide covers troubleshooting for reverse proxy services.

== 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''':
<pre class="lang-bash">
==== 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
</pre>

=== Issue: SSL Certificate Failed ===

'''Causes''':
* DNS not pointing to VPS

* Port 80 blocked

* Rate limiting from Let's Encrypt

'''Solutions''':
<pre class="lang-bash">
==== 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
</pre>

=== Issue: Service Not Loading ===

'''Causes''':
* Wrong proxy_pass URL

* Missing headers

* Service requires specific path

'''Solutions''':
* Check Caddy: <code>journalctl -u caddy -n 50</code>

* Verify backend directly: <code>curl http://127.0.0.1:PORT</code> (VPS) or <code>curl http://10.8.0.2:PORT</code> (NAS via VPN)

* Test with different proxy_pass formats

=== Issue: Connection Timeout ===

'''Causes''':
* VPN tunnel down

* Service not accessible

* Firewall blocking

'''Solutions''':
<pre class="lang-bash">
==== 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
</pre>

== Diagnostic Commands ==

<pre class="lang-bash">
=== 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
</pre>

== Related Documentation ==

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

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

[[Category:Documentation]]
[[Category:Documentation/Troubleshooting]]