HomeAssistant URL cannot be accessed via Wireguard/Pihole

Hi everyone,

I have the following problem.
I can access the homeassitant.local or other custom URLs in the homeassitant in the WLAN normally.

Unfortunately, this is not possible via Wireguard (set up via Fritz!Box).
I can call homeassistant.fritz.box:8123, but not homeassitant.loacl:8123.

Settings:
-PiHole is entered as the local DNS on the FB
-In Pihole homeassistant.loacl is defined as DNS record
-FB is again the DNS upstream in Pihole
-Wireguard used integrated in the FB

I have tried a few things and am really at a loss.
Can anyone help me?
Thanks in advance