This thread discusses the same problem with apache web server:
https://serverfault.com/questions/751170/apache-linux-httpd-listen-on-link-…
The conclusion was that this kind of syntax works:
/etc/httpd/conf/httpd.conf:Listen fe80::a00:16ff:fe89:420f%3:80
that is, ipv6 address without the brackets followed by the interface
name.
I could try that with K, but it does not accept that kind of listen
address syntax.
-- Juha