---
title: "Fixing 5xx errors caused by your firewall — Lemwatch Help"
description: "Diagnose 502, 503, and 520 responses that only appear in Lemwatch — usually WAF rate limits or origin timeouts."
canonical: "https://lemwatch.com/help/fixing-5xx-errors-from-firewall"
source: "https://lemwatch.com"
---

# Fixing 5xx errors caused by your firewall

> Diagnose 502, 503, and 520 responses that only appear in Lemwatch — usually WAF rate limits or origin timeouts.

## Quick answer

 5xx errors that only Lemwatch sees are usually your WAF rate-limiting our probes or your origin timing out. Whitelist Lemwatch IPs, then look at the exact status code — 502/504 point to origin, 520–524 point to Cloudflare.

## What each code means

- 502 Bad Gateway — origin returned an invalid response

- 503 Service Unavailable — rate limit or maintenance

- 504 Gateway Timeout — origin didn't reply in time

- 520–524 — Cloudflare-specific: origin unreachable, SSL handshake, or timeout

- 530 — Cloudflare 1xxx error nested inside a 530 response

## Where to find it in Lemwatch

 **Site → Incidents → open the incident → Response details** shows the exact status, headers, and CF-Ray ID.

## How to fix it

- Copy the CF-Ray or request ID from the incident.

- Whitelist Lemwatch IPs (see IP whitelisting ) — resolves most 503/520.

- For 502/504, check origin server logs at the incident timestamp for slow queries or crashes.

- For 522, raise your origin's TCP keepalive and Cloudflare's Proxy Read Timeout.

- Run Check now to confirm the error clears.

## FAQ

### Why does the site load fine for me but Lemwatch sees 503?

 Your browser is likely cached at Cloudflare's edge or exempt from the rate limit — Lemwatch's probes are not.

### Should I disable my WAF to test?

 No — just add a Skip rule for Lemwatch IPs and re-test.

## Related

- Cloudflare blocking Lemwatch

- Whitelist Lemwatch monitoring IPs

- Site shows down but is actually up


## Related

- [Help centre](https://lemwatch.com/help)
- [Cloudflare is blocking Lemwatch checks](https://lemwatch.com/help/cloudflare-blocking-lemwatch)
- [Whitelist Lemwatch monitoring IPs](https://lemwatch.com/help/lemwatch-ip-whitelisting)
- [My Site Shows as Down But It's Working](https://lemwatch.com/help/site-shows-down-but-working)
- [Why did my SSL grade drop?](https://lemwatch.com/help/why-ssl-grade-dropped)
- [Bypassing bot protection for Lemwatch checks](https://lemwatch.com/help/bypassing-bot-protection)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [Flapping detection](https://lemwatch.com/help/flapping-detection)