Unable to install Acronis Backup extension in Plesk: Failed to connect to host “45.11.1XX.XX” via port <port_number> – Plesk

Symptoms

• Unable to install Acronis Backup extension due to the following error:

  Failed to connect to host "45.11.XXX.XX" via port <port_number>.
  Please update your firewall configuration and restart the installation.

  Note: the IP address and port may vary

• Trying to connect to the IP address from the error message via telnet utility fails from any machine:

  # telnet 45.11.XXX.XX <port_number>
  Trying 45.11.XXX.XX...
  telnet: connect to address 45.11.XXX.XX: Connection refused

Cause

A temporary issue on Acronis CDN.

Resolution

Try reinstalling the extension again after a few hours.

As a workaround, perform the following steps:

1. Connect to the server via SSH

2. Add the following lines to /etc/hosts:

   45.11.XXX.XX eu2-cloud.acronis.com
   45.11.XXX.XX eu2-cloud.acronis.com
   45.11.XXX.XX eu2-cloud.acronis.com

   Note: replace the 45.11.XXX.XX placeholder with the actual IP address mentioned in the error message

3. Install the Acronis Backup extension again