DHCP client finds no DHCP server

Hello

I have a Router with wifi from my ISP and want to extend the network. For that I use an hAP lite.

I have router OS 6.45.8 on the hAP lite.
1.) Setup an Securty profile for my Wifi network.
2.) I set the Wlan1 to “Station” mode an named the Right SSID + Security Profile.
3.) Wlan1 changed to Slave Running.
4.) IP->DHCPClient-> Bridge add (wlan1 is not possible since it is Slave)

Now the DHCPClient is searching for an IP but doesn’t get one. How can i figure out what is going on/wrong?

best regards