Happy to help.

You can find more information here: https://en.wikipedia.org/wiki/Multicast_DNS

You can learn how to configure it here: https://wiki.archlinux.org/title/Avahi

I see why some people can be confused though. In some distros it needs to be configured. Once you configure it though it should be rock solid.

There is no reason why an ICMP packet would be more robust than a multicast udp packet.

The traditional nomenclature is myhostname.local

Just make sure that the system firewall is configured to allow mdns. That’s the biggest issue. Once you have e that and you have mdns set up it’s good to go.

link local

IPv4 has this too. It's normally not routable so it's safe to ignore in both IPv4 and IPv6.

Instead of DHCP...

The following is a gross simplification, but works for understanding the most common cases:

The original (heavy emphasis on this word) idea of IP is that addresses are unique for every interface. Additionally MAC addresses (48 bits) are also unique for every interface.

In IPv4, you're trying to make interfaces that are unique in 48 bit IDs unique in 32 bit IDs. It doesn't take a pigeon to realize there will be collisions. Therefore you need a person to manually assign addresses. If you automate that person, that becomes DHCP.

In IPv6, you're making a 48 bit unique ID unique in a 128 bit namespace. You literally don't need to do anything and you can still guarantee it's unique. That's how you automatically assign IPv6 addresses without DHCPv6.

As for how MAC addresses are assigned uniquely, the first 24 bits are a vendor prefix. The vendors then ensure each device they produce is unique.

With ipv6 the address is too long and incomprehensible to remember.

The problem is that nobody should be memorizing arbitrary 128 bit numbers, or even 32 bit arbitrary numbers. Especially since the numbers don't even correspond to a machine, but instead an interface on the machine. Yes, 32 bit IPv4 addresses are easier to memorize, but you shouldn't be memorizing them in the first place. Services run off of names. If the names aren't working, fix the name service.

Ideally NDN solves this problem completely. Every host/packet is identified by a name, not an address. If you need to fetch something, all you need to do is provide the name and somebody (doesn't have to be the original machine) will provide it to you.

Have faith in yourself. I bet you could get things in a few hours with focused study if you have a deep understanding of IPv4.

my response is basically not until I understand it...

That was probably a good call, firewalling and (lack of) DHCP especially is quite different so just trying to use v4 concepts on v6 addresses/networks is almost a guaranteed bad time