Is SSH Access used for UMS or other utilities or can it be turned off?
SSH is only used for SSH connections from external clients and can be disabled.
You can learn more here:
Secure Shell (SSH) Access to IGEL OS with Keys
IGEL OS has a built-in OpenSSH server that can be activated and configured via the Setup application. It lets you connect securely to the device over the network in order to issue commands or transfer files. While authentication can be done with a username-password combination, using a private-public key pair can increase convenience and/or security. This document describes how to generate and distribute the keys required. – kb.igel.com/igelos-11.03.100/en/secure-shell-ssh-access-to-igel-os-with-keys-24385093.html
Configuring SSH Access on the Device – kb.igel.com/igelos-11.03.100/en/configuring-ssh-access-on-the-thin-client-24385097.html