EPEL (Extra Packages for Enterprise Linux) is a volunteer-based community effort from the Fedora project to create a repository of high-quality add-on packages that complement the Red Hat Enterprise Linux (RHEL) and its compatible spinoffs, such as Oracle Linux, Rocky Linux, AlmaLinux and CentOS.
The majority of ProComputers images built before 31st of December, 2022 contains the EPEL repository preinstalled. However, all images with a release date after 1st of January 2023, will not have the EPEL repository included by default.
NOTE: The image release date is part of the image version. Read this article to learn how find out the image version.
If you still want to use the EPEL repository, then the official manual installation instructions for versions 7, 8 and 9 can be found here.