In Aegir 7.x.3.11, We are using the PHP 5.6 version in ubuntu 14.04 in which we have drupal 7 & 8 sites.
While upgrading the PHP version, the PHP repository is not supported for this ubuntu version.
So we planned to upgrade ubuntu 18.04 with Aegir's latest version.
Needs steps to upgrade latest Aegir on ubuntu 18.04