This appears to be similar to
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1067873
However, I am running a desktop system that only has an IPv4 address and KDE Connect is working fine (after fixing the nftables problem described in #1067873). So, this appears to end up being a system firewall issue instead of a KDE Connect issue.
--
Soren Stoutner
soren@debian.org
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