I found issue in connecting kde-connect in windows because i dont have inbuilt wifi on motherboard and sometime i connect wifi later when required.
now as kde-connect is set to run as startup app so we dont have to open it each time. the problem is my wifi dont start immediately at startup (when kde was already loaded) so it remain disconnected even after sometime wifi gets connected.
the solution i find is to make KDEconnect check after 2-5 mins of startup whether the PC is connected to wifi or not. there maybe some option in system tray to check for connection for manual connection.