Resolve Domain and Hostnames in Reporting , wrong DNS settings?

Hi there,

i have the following setup:

UTM 9.5 which runs between the modem and the wlan router/switch. UTM is set up in transparent mode.

I run a DNS "server"/internal forwarder (pihole, details at https://pi-hole.net/ ) at 192.168.0.115 on a raspberry pi, which blocks ads and malware.

DHCP server is setup in UTM, domain name is set in DHCP settings as: myutm.local

Also, in the DHCP server settings, 192.168.0.115 is set up as the primary DNS (with 8.8.8.8 as the secondary DNS)

DNS settings:

Global --> Allow internal network

Forwarder --> Retreive DNS addresses from the ISP

I would like to keep using the pihole, and i would like to have the IP addresses resolved in the firewall reports in the UTM.

Do i have to set up the pihole also in the UTM DNS forwarder settings? Or do i keep this setting empty? 

Do i have to set up additional entries in the route request tab in the DNS settings?

I there tried to set up Domain --> 0.168.192.in-addr.arpa and as target server my pihole dns server. That did not work, as the reports keep showing just the IP adresses. 

Any ideas how to solve this?