My ER605 is setup in Omada Software Controller 5.9.31.  I was trying to find to customize the WAN online detection not only the interval time but the ping or dns to be customized. If not possible, what is the basis if the primary interface fails? is that based when  physical WAN port is down or the next hop is not reachable or other else?

In ER605 standalone i can see this feature to customize ping and DNS.