It looks like there is a mismatch between the AWS classic load balancer timeout and the org.atmosphere.websocket.maxIdleTime that results in com.vaadin.server.communication.PushAtmosphereHandler - Exception in push connection errors.
The setting should be configured in the web.xml as an init-param (stated in the JavaDoc in org.atmosphere.cpr.ApplicationConfig) - is it possible to configure it in the application.properties of the Jmix project also?
