mDNS is like the LLM of DNS: sometimes, for some audiences, it works well, but when it doesn't work you're SoL trying to fix it other than "have you tried $(sudo killall -INT mDNSResponderHelper)?"

I'm not aware of any DHCP change needed for that, since to the very best of my knowledge mDNS is a broadcast protocol. Involving DHCP would be pointing it at the copy of dnsmasq running on your router, such that the hostname that the devices present to DHCP are then resolved by dnsmasq, no mDNS required