add actioncable for prod

config/routes.rb

 Rails.application.routes.draw do
-  get 'speakers/show'
   mount Crono::Engine, at: '/crono'
+  mount ActionCable.server => '/cable'
+
+  get 'speakers/show'
 
   get 'login', to: 'users#login', as: :login
   post 'login', to: 'users#login'