The SMnetSetup utility is the designated command-line tool for configuring the fundamental network settings of an Avaya Breeze™ server, including its IP address, netmask, and default gateway. To correct the default gateway, a technician must establish an SSH session to the affected Breeze server using administrative credentials and execute the SMnetSetup command. This tool ensures that the network configuration changes are correctly applied and are persistent across system reboots, which is the standard and supported Avaya procedure for this task.

B. Using the route command would only make a temporary change to the routing table that would not persist after a reboot. It is not the standard procedure for permanent network configuration.

C. The SIP Entity screen in Avaya Aura® System Manager is used for configuring application-level SIP signaling parameters, not the underlying operating system's network settings like the default gateway.

D. The Engagement Development Platform administration in System Manager is used to manage the Breeze cluster, nodes, and services at the application layer, not for core OS-level network configuration.

1. Avaya Documentation: Deploying and Configuring Avaya Breeze®, Release 3.7, November 2019.

Reference: Chapter 4: Installing Avaya Breeze® on an Appliance Virtualization Platform, Section: "Post-installation tasks for Avaya Breeze®", Page 51. The document states, "Log on to the server by using the command line interface. Run the /sbin/SMnetSetup command to configure the network interfaces." The subsequent steps detail the configuration of the IP address, netmask, and gateway.

2. Avaya Documentation: Administering Avaya Aura® Session Manager, Release 8.1.3, December 2020.

Reference: Chapter 3: Initial configuration, Section: "Network configuration for Session Manager", Page 35. The guide specifies, "Use the SMnetSetup utility to configure the IP address, netmask, and default gateway for the management interface of the Session Manager server." (Note: The SM100 is a Security Module for Session Manager and shares its fundamental administration tools).