I had the application working and then the version 1.8 came out and 1.3 on debian. Since then they NEVER connect. It is not a networking problem as using wireshark I do see devices exchanging message both ways, but no device discover each other. I have installed it on 3 android devices with different os version (7.0, 8.0, 8.1) and on 2 Linux PC and result is always the same. The Linux application do see other Linux application (children PC). I staed to experiment beta version 1.9 on android and git compiled myself on debian, no change. Rebooting, restarting apps, phone no change. Communication with the same device via DLNA, ssh do work normally. Bug is open on debian but no solution. contacted development mailing list but proposed test do not solve anything.
After testing another android device, and having my son use it's Linux PC while I was doing some test, I can add the following information: 1) Linux PC do see other Linux PC on the network, no matter whether wired or wireless, 2) Android devices do see each other (wireless 2.4Ghz device talk with 5 Ghz devices so go through the router), But Linux device and android device do not see each other. Looks like there is a bug on the packet structure that goes on the wire when android talks to linux and vice versa (I do see devices exchanging info via wireshark). I'm using 64 bits amd64 linux kernels and apps and for android they are all 32 bits (kernel and apps).
The same happens to me. Devices don't see each others anymore. It seems happening after the latest update of Kdeconnect on Android (the former was fully functional). PC: Kubuntu 18.04 [frapox@tungsteno ~]$ kdeconnect-cli --version kdeconnect-cli 1.3 Smartphone: Android 8.1 org.kde.kdeconnect_tp version 1.8.4
Tested both 1.3.1 on Linux and 1.9 beta on android. No change. Two separate worlds : linux devices sees each other, android devices see each other, but no Linux <-> working.
*** This bug has been marked as a duplicate of bug 389010 ***