Kde Connect
KDE Connect is a tool that allows users to connect their Linux systems with other devices, which may be another system running Windows, macOS, Linux, or Android. KDE Connect is a useful tool developed by the people working at KDE that easily allows communication between many different kinds of devices.
Problem
After installing KDE-connect to both your PC and phone and on same network but still not able to connect. As when you open KDE-connect it does not show any device.
Reason
KDE Connect uses dynamic ports in the range 1714–1764 for UDP and TCP. So if you are behind a firewall, make sure to open this port range for both TCP and UDP. Otherwise, make sure your network is not blocking UDP broadcast packets.
Solution
Make some changes in IPtables;
Run following 2 commands in your terminal.
sudo iptables -I INPUT -p tcp --dport 1714:1764 -j ACCEPT
sudo iptables -I INPUT -p udp --dport 1714:1764 -j ACCEPT
And that’s it now you hopefully see the devices, now you can pair it and start using it.