@shberge Thanks for your response but isn't the controller management the Omada (software) controller? How would I even attempt an upgrade without logging into it first? Which means I already have full local access to it (https://localhost:8043). And I never had to do anything special before to do an upgrade. So the Omada Controller HTTPS for Management is already open. Once logged in I go to Devices -> ER605 -> Config -> Manage Device and click Browse to select the custom firmware file. I've also tried just clicking the Up arrow button beside my ER605 device to run the Upgrade.

  @yorkman 

this is new not long ago, the devices to be upgraded must have access to this port on the controller, so you need to check that you can reach the controller from the network the devices are connected to. you are on localhost and it is directly on the server, that does not mean that the router has a connection with the controller on port 8043

  @shberge Thank you for your help. You were right, and the problem has been resolved.

  @yorkman