When setting up or updating the firmware on a Linksys Velop mesh system, users frequently encounter Linksys error 2123. An interrupted installation procedure or issues with node-to-node connection are usually the causes of this error. Make sure every node is turned on, have a steady internet connection, then reload the configuration to fix it. https://velosetup.com/getting-linksys-error-2123-during-router-login-lets-fix/