I don't understand why all my devices randomly assign themselves non-functional IPv6 addresses with no involvement from any router. Often it's even multiple non-functional IPv6 addresses.
IPv6 assigns link-local addresses automatically. They are for talking to other computers on same the network. It works when you don't have router. It won't interfere with anything else.
IPv6 supports multiple addresses on each machine for different scopes: global, internal, local. IPv6 uses address hierarchy to figure out which one to use to reach destination.
