I am using siducation (debian sid) and when I try to the pair the request expire. Both desktop and android phone can find each other but when I try to pair on clicking the notification (on both the case) the request finish without any alert. I see only that they saw each others. I don't have any error printed and I am not sure where to check for a log. Ref: https://www.reddit.com/r/linux/comments/9bkcup/kde_connect_ama/e54cder/?context=10000
There is the firewall on the router but I guess that if was blocking something the pairing with the notification should have problems as well.
Hello from KDE's bug team! The KDE Connect page in System Settings was recently removed, in favor of a new standalone app used to configure KDE Connect. As such, this Bugzilla ticket is no longer relevant due to the software it's about no longer existing. Please open new bug reports for the desktop ap at https://bugs.kde.org/enter_bug.cgi?product=kdeconnect&component=desktop-application. Thanks!