Based on
My outputs:
sudo netstat -tunelp | grep -i kdeconnect
tcp6 0 0 :::1716 :::* LISTEN 1000 25622 1035/kdeconnectd
udp6 0 0 :::1716 :::* 1000 25621 1035/kdeconnec
netcat -z -v 192.168.0.13 1714-1764
latitux.local [192.168.0.13] 1716 (xmsg) open
KDE Connect listens to 1716 and it seems to be open.