Yeelight 480 ceiling lamp - does not show up in Yeelight App

My new Yeelight 480 ceiling light arrived today but unfortunately I can not connect it to the Yeelight app (IOS). I already successfully connected the remote control. In the app, however, the lamp is not displayed and therefore I can not connect to it.
I use the german server.

When adding I choose my home wifi and enter my wifi password. Then the app looks for the lamp but does not find it.

In my mobile wifi settings, the lamp is detected. The wifi function of the lamp itself seems to work. I also reset the lamp, but this didnt help either.

Do I have to make certain settings in my router? Does my router block the lamp if necessary and it is therefore not displayed?
I attach a screenshot of my router settings.

I hope you can help me!

Please have a check if the bulb is shown in your router’s DHCP list after connection.