I have an issue with the hotspot on my little server:

The hotspot is configured and I think it's ready to work, only the DHCP is missing. dnsmasq is not starting:
dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server
Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Tue 2023-04-18 15:32:15 CEST; 27s ago
Process: 11254 ExecStartPre=/etc/init.d/dnsmasq checkconfig (code=exited, status=0/SUCCESS)
Process: 11262 ExecStart=/etc/init.d/dnsmasq systemd-exec (code=exited, status=2)
CPU: 20ms
Apr 18 15:32:15 Zentrale01 systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
Apr 18 15:32:15 Zentrale01 dnsmasq[11262]: dnsmasq: failed to create listening socket for 10.42.0.1: Die Adresse wird bereits verwendet
Apr 18 15:32:15 Zentrale01 systemd[1]: dnsmasq.service: Control process exited, code=exited, status=2/INVALIDARGUMENT
Apr 18 15:32:15 Zentrale01 dnsmasq[11262]: failed to create listening socket for 10.42.0.1: Die Adresse wird bereits verwendet
Apr 18 15:32:15 Zentrale01 systemd[1]: dnsmasq.service: Failed with result 'exit-code'.
Apr 18 15:32:15 Zentrale01 dnsmasq[11262]: Start fehlgeschlagen
Apr 18 15:32:15 Zentrale01 systemd[1]: Failed to start dnsmasq - A lightweight DHCP and caching DNS server.
How can I solve this and run Pi-hole + DHCP on the system and how can I make the bridge in between the networks?