Upgrading Version 7.20A Stream to Version 7.4
For upgrading the device from the Version 7.20A stream (based on CentOS 6) to Version 7.4,
For upgrading your device from the Version 7.20CO stream (based on CentOS 8) to Version 7.4, use the Web-based interface's Software Upgrade Wizard, as described in Upgrading the Device's Software.