How To Resolve Connection Errors When Adding a New Server to Plesk 360

If you're encountering connection errors while attempting to add a new Plesk server to Plesk 360, or if a previously added server shows a "Connection Error" status, it's likely due to network restrictions or firewall settings. This guide will help you identify and resolve these common issues.

Common Error Messages

When adding a new Plesk server to Plesk 360, you might encounter one of the following errors:

The connection to the server $server.$hostname.com cannot be established correctly. Plesk version is not supported (below 18.0.37) or Plesk is misconfigured.
The network connection to the server timed out.
Unknown error: connect ECONNREFUSED 213.0.1.2:443

For servers already added to Plesk 360, you may see the following under Server state:

Connection error

Under Plesk 360 > Server > $server.$hostname.com, the message might read:

The connection to the server server.hostname.com cannot be established correctly. The server is configured incorrectly or you have entered an incorrect address.
Please fix the error and press the button below to restore the connection.

Possible Causes

These errors usually indicate that access to the server is restricted in one of the following ways:

• Firewall Rule Blocking Connections - A firewall on the server or network level may be blocking inbound or outbound connections required by Plesk 360.
• Fail2Ban Bans - Fail2Ban may have banned the IP addresses required for Plesk 360 communication.
• IP Access Restriction Management - IP addresses used by Plesk 360 may be blocked by IP access restrictions in the Plesk admin panel.
• API Filtration Rules - API filtering rules may be configured to prevent necessary communication with Plesk 360.

Resolution Steps

To resolve these errors, follow the steps below to allow access for Plesk 360's IP addresses:

1. Allow Plesk 360 IP Addresses in Firewall
   Ensure that your firewall allows inbound and outbound connections from the IP addresses used by Plesk 360:

   
   52.51.23.204
   52.213.169.7
   34.254.37.129
           

   If you're using the Plesk Firewall extension, add these IPs to the allowed list.
2. Add Plesk 360 IPs to Trusted IPs in Fail2Ban
   
   • Navigate to Fail2Ban settings in your Plesk control panel.
   • Add each of the Plesk 360 IP addresses to the Trusted IP Addresses list.
   This prevents Fail2Ban from blocking these IPs, ensuring uninterrupted communication with Plesk 360.
3. Allow Access in IP Access Restriction Management
   Go to Plesk > Tools & Settings > IP Access Restriction Management and ensure that Plesk 360's IP addresses are allowed under the access settings for Administrative Access. This will prevent the IP addresses from being blocked when they attempt to connect.

Additional Notes

By ensuring these IP addresses are permitted in your firewall, Fail2Ban, and IP access settings, you should be able to resolve connection errors and add your server to Plesk 360 successfully.

Disclaimer

Always verify IP settings and restrictions in a test environment when possible. Refer to the latest Plesk documentation to confirm compatibility with your server configuration and Plesk version.