Hi @MiFri,

If you only have one EAP245, the controller is not a necessaey choice, you may use the Omada App on the phone to add the EAP.

Please use your phone connect or laptop to connect to the EAP’s Wi-Fi. If you can not find the WiFi or can not remember the password, you may reset the EAP and set it up again.

How to reset: please press the reset button on the EAP for 4 seconds and make sure the LED light changes, EAP's WiFi name will back to the default one tplink_5G and without a password.

Now use the phone to connect to the default WiFi and if you can see the error message “Obtain IP address fails”, or the phone can connect it but the IP address is 169.254.x.x. It is because the connection between the router and EAP fails. Please check the physical connection from the router to the EAP. If you are not sure, please use a PC to replace the EAP, connecting with the same Ethernet port and cable to check the PC can get internet or not.
 
If you can connect to the EAP’s Wi-Fi but no internet, please check the IP address on the phone or PC.
How to find IP address of Android smartphone/iPhone/iPad

Here is the instruction of the EAP setup.