I have been using Kde Connect for the past 6 months on my Sony Experia E5 and my Samsung Galaxy Note 3. My Note 3's Kde Connect suddenly stopped working. It now can't find other devices or be found by other devices. I installed an older version of Kde Connect and that still didn't fix the problem. Kde Connect on my Linux Mint PC and Sony phone function properly.

One thing that can work to fix KDE Connect is to clear the app data on your phone, and remove the pairing on the computer.
This basically resets things, and often fixes this sort of problem by creating a clean pairing setup. I find that I have to do this on occasion, mainly when there has been an update to the phone app or the PC software.

I did clear the data on my phone and reinstalled. I also deleted the pairing. My sony or my pc still can't see the note 3.