This article explains how to troubleshoot and resolve a common issue where 360 Monitoring reports a website as down with a 403 Forbidden error, despite the website being fully accessible through web browsers and cURL. This problem typically affects websites proxied through Cloudflare and is related to IPv6 configuration mismatches.
Symptoms
- The domain is proxied behind Cloudflare (orange cloud-enabled)
- 360 Monitoring consistently reports the website as down with a 403 Forbidden error
- The website loads correctly when accessed through a web browser
- The website can be accessed successfully using cURL from your local machine
- The domain only has an IPv4 address assigned in Plesk
Root Cause
This issue occurs because Cloudflare automatically creates both IPv4 (A) and IPv6 (AAAA) DNS records for proxied domains. When 360 Monitoring attempts to check the website, it may use the IPv6 address provided by DNS resolution, but if the server doesn't have an IPv6 address configured in Plesk, this results in a 403 Forbidden error.
Verifying the IPv6 Resolution
You can confirm this is the issue by checking if your domain resolves to an IPv6 address despite not having one configured in Plesk:
# Check if the domain resolves to an IPv6 address
dig @8.8.8.8 +short -t AAAA example.com
# Example output showing an IPv6 address exists:
2001:db8:f61:a1ff:0:0:0:80If this command returns an IPv6 address (as shown in the example), but your server doesn't have an IPv6 address configured in Plesk, this confirms the root cause of the problem.
Resolution Options
There are three ways to resolve this issue. Choose the option that best fits your needs:
Option 1: Configure 360 Monitoring to Use IPv4 Only (Recommended)
- Log in to your 360 Monitoring dashboard
- Navigate to Websites
- Find and click on the affected website in the list
- Go to the Settings tab
- Click Show advanced options to display additional settings
Location of the "Show advanced options" button in website settings
- In the IP Version dropdown menu, select IPv4
Setting the IP Version to IPv4 only
- Click the Update button to save your changes
- Wait for the next monitoring check cycle (typically 1-5 minutes, depending on your plan)
Option 2: Remove AAAA Records from Cloudflare
If you don't need IPv6 support for your website, you can remove the AAAA records from Cloudflare:
- Log in to your Cloudflare dashboard
- Select the domain you want to modify
- Go to the DNS tab
- Find the AAAA records for your domain (they will show IPv6 addresses)
- Click the Delete icon (trash can) next to each AAAA record
- Confirm the deletion
- Allow time for DNS changes to propagate (can take up to 24 hours, though often much quicker with Cloudflare)
Note: If you're using Cloudflare's CNAME setup or Full DNS integration, new AAAA records might be automatically created again. In this case, Option 1 (configuring 360 Monitoring) is preferred.
Option 3: Add IPv6 Address in Plesk
If you want to properly support IPv6 for your website (recommended for future compatibility), you can add an IPv6 address to your server in Plesk:
- Verify that your hosting server has IPv6 connectivity and an available IPv6 address
- Log in to Plesk as an administrator
- Go to Tools & Settings > IP Addresses
- Click Add IP Address
- Enter the IPv6 address and other required information
- Select the domain(s) that should use this IPv6 address
- Click OK to save the changes
- Restart the web server if required
Important: Adding an IPv6 address requires that your server has IPv6 connectivity. Contact your hosting provider if you're unsure about IPv6 availability or configuration.
Verifying the Fix
After implementing one of the solutions above, verify that the issue is resolved:
- Log in to your 360 Monitoring dashboard
- Navigate to Websites
- Check the status of the previously affected website
- If the status is still showing as down, you can force an immediate check:
- Click on the website name
- Click the Check Now button
- Verify that the website now shows as up and running with a 200 OK status
Website showing as "Up" in 360 Monitoring after implementing the fix
Preventing This Issue
To prevent this issue from occurring with future website monitoring setups:
- For Cloudflare-proxied websites: Always configure 360 Monitoring to use IPv4 only if you don't have IPv6 configured on your server
- When setting up new websites in Plesk: Check if IPv6 is available on your server and configure it properly
- For new 360 Monitoring configurations: When adding a new website to monitor, check the advanced options and set appropriate IP version settings based on your infrastructure
Pro Tip: Consider implementing IPv6 on your web servers when possible. IPv6 adoption continues to grow, and having proper IPv6 support ensures compatibility with all monitoring systems and future-proofs your web infrastructure.
Related Issues
This IPv6/IPv4 mismatch can cause other monitoring and connectivity issues:
- Email deliverability problems: Mail servers might attempt IPv6 connections that fail
- API connectivity issues: Third-party services may encounter similar 403 errors
- CDN edge case problems: Content delivery networks might face inconsistent connectivity
The solution is similar in all cases - either configure services to use IPv4 only or properly implement IPv6 support.
Conclusion
The "403 Forbidden" error in 360 Monitoring for Cloudflare-proxied websites is typically caused by an IPv6 addressing mismatch. By configuring 360 Monitoring to use IPv4 only, removing AAAA records from Cloudflare, or properly implementing IPv6 in Plesk, you can resolve this issue and ensure accurate monitoring of your websites.
For further assistance with 360 Monitoring or Plesk configuration, please refer to our other knowledge base articles or contact technical support.
