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Using NetworkManager and systemd-resolved together in Debian bookworm does not work out of the box. The first sign of trouble was these constant messages in my logs: avahi-daemon[pid]: Host name conflict, retrying with hostname-2 Then I realized that CUPS printer discovery didn't work: my network printer could not be found. Since this discovery now relies on Multicast DNS , it would make sense that both problems are related to an incompatibility between NetworkManager and Avahi . What didn't work The first attempt I made at fixing this was to look for known bugs in Avahi. Neither of the work-arounds I found worked: the one proposed in https://github.com/avahi/avahi/issues/117#issuecomment-1651475104 : [publish] publish-aaaa-on-ipv4=no publish-a-on-ipv6=no nor the one proposed in https://github.com/avahi/avahi/issues/117#issuecomment-442201162 : [server] cache-entries-max=0 What worked The real problem turned out to be the fact that NetworkManager turns on full mDNS support in systemd-resolved which conflicts with the mDNS support in avahi-daemon . You can see this in the output of resolvectl status : Global Protocols: LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Link 2 (enp6s0) Current Scopes: DNS mDNS/IPv4 mDNS/IPv6 Protocols: +DefaultRoute -LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 192.168.1.1 DNS Servers: 192.168.1.1 DNS Domain: lan which includes +mDNS for the main network adapter. I initially thought that I could just uninstall avahi-daemon and rely on the systemd-resolved mDNS stack, but it's not actually compatible with CUPS . The solution was to tell NetworkManager to set mDNS to resolve-only mode in systemd-resolved by adding the following to /etc/NetworkManager/conf.d/mdns.conf : [connection] connection.mdns=1 leaving /etc/avahi/avahi-daemon.conf to the default Debian configuration. Verifying the configuration After rebooting, resolvectl status now shows the following: Global Protocols: LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Link 2 (enp6s0) Current Scopes: DNS mDNS/IPv4 mDNS/IPv6 Protocols: +DefaultRoute -LLMNR mDNS=resolve -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 192.168.1.1 DNS Servers: 192.168.1.1 DNS Domain: lan Avahi finally sees my printer (called hp in the output below): $ avahi-browse -at | grep Printer + enp6s0 IPv6 hp @ myprintserver Secure Internet Printer local + enp6s0 IPv4 hp @ myprintserver Secure Internet Printer local + enp6s0 IPv6 hp @ myprintserver Internet Printer local + enp6s0 IPv4 hp @ myprintserver Internet Printer local + enp6s0 IPv6 hp @ myprintserver UNIX Printer local + enp6s0 IPv4 hp @ myprintserver UNIX Printer local and so does CUPS: $ sudo lpinfo --include-schemes dnssd -v network dnssd://myprintserver%20%40%20hp._ipp._tcp.local/cups?uuid=d46942a2-b730-11ee-b05c-a75251a34287 Firewall rules Since printer discovery in CUPS relies on mDNS, another thing to double-check is that the correct ports are open on the firewall. This is what I have in /etc/network/iptables.up.rules : # Allow mDNS for local service discovery -A INPUT -d 100.64.0.0/10 -p udp --dport 5353 -j ACCEPT -A INPUT -d 192.168.1.0/24 -p udp --dport 5353 -j ACCEPT and in etc/network/ip6tables.up.rules : # Allow mDNS for local service discovery -A INPUT -d ff02::/16 -p udp --dport 5353 -j ACCEPT RSS Atom this is a little over my head, so trying to learn a bit, I searched the Wiki. It needs some help, nothing about this issue is mentioned. https://wiki.debian.org/NetworkConfiguration#Using_systemd-resolved_for_DNS_resolution can you add something to help others? Add a comment