@LMue 

Hey

Repeaters are not used in Business grade hardware, that is more home grade stuff.   In Omada this is a MESH setup you are referring too and will require a controller online to manage the WiFi clients.

To do this, if you have not already, adopt the first AP into the Controller.

Then go to SETTINGS and under SITE  tick the box beside MESH..  also enable ADVANCED FEATURES and tick Fast Roaming, AI Roaming and Band Steering

Power on 2nd AP..   after a few mins it should be available to adopt via Wireless, your MESH is now online

@Philbert 

Thanks for you reply.

i can't adopt any device to the controller, that is what i was asking about.

the controller can not find the device(s). The list is just empty. No matter if the devices are on default (after reset) or already in my IP range. I have tried all day today to get one or both devices into the controller.
Both APs are connected to my network via the PoE injector, but still the controller and also the device search tool can't find the APs.

How should it work? Simply connect devices to the network in the default state?
ps: my network has no DHCP!

@LMue 

What should I do when the Omada Software Controller (V4) fails to discover the devices?

To discover, PC runs the OSC has to be in the same network as your EAP. They're required to be plugged into the same device. PC will broadcast packets to all the clients in the network. 

Literally, I don't know if there's no DHCP server that will still apply the rules I mentioned above. I never tried that. If you confirm these necessary requirements are done right, it results from the no DHCP server.