@VolkerS It's not certain that you have it, do you have the latest version on your controller and router? Try and upgrade your router to the latest version first

@VolkerS enable ARP Detection on network interface, adavanced settings

@Alfred_DOMO you have to run enable first then roll-back

@VolkerS yes that was strange, SG2428P should show you the ip address of the clients, i have such a switch myself. have you tried restarting everything, switch access points and controllers. you can...

@VolkerS try upgrading the controller and router to the latest version, It is a relatively new feature

@AndyBH that was strange, with the internet settings you have, you should only use the backup wan when the primary wan is down. so there is actually no need for policy route either. try running...