Hi @GvB 

Thanks for posting in our business forum.

Then use a static line for the primary connection. Or preconfigure on the Omada Cloud-based Controller (if you are talking about the Cloud-based Controller).

There is no better solution to this. The thing is that adopting will reset. Resetting will make you lose the config. How to Add Omada Devices to Omada Cloud-Based Controller

If you mess up the controller type, and you are talking about the local controller. Then you don't have to worry about Internet access. Only when the CBC scenario, you should worry about Internet access because the controller is based on the cloud.

Till I am typing here, are you saying that you use 4G backup WAN as your primary?? Wait, what?

GvB wrote

This time I had the surprise of losing the connection to my ER605 router due to the fact that the 4g modem / usb port didn't worked after the migration to the Omada cloud This time I had the surprise of losing the connection to my ER605 router due to the fact that the 4g modem / usb port didn't worked after the migration to the Omada cloud.

I don't get it at all.. USB modem can ONLY be used as a backup. If you have a normal link as Dynamic IP, that would not be a problem. Your description does not make sense.

Just do it from the local network and refer to the manual if you are new to something. Instead of making a statement that is headless.