Good day,

KDE connect works fine here usually. A desktop and a laptop here can exchange data/pictures/files etc without any problems. On both runs Kubuntu 18.04. Sending data to those machines from smartphone is no problem either.
However: sending data from both machines to my smartphone does not work. What goes wrong here?

second problem: I have an old machine for backups. ON this one runs debian (8?) with plasma KDe. This machine is able to send files to all my other machines and to my smartphone and it can receive from my smartphone. But it cannot receive data from my other two machines: the desktop and laptop.

All the devices can communicate by using KDE connect apart from the problems with data transfer. All three computers should have their firewalls configured for allowing incoming and outgoing data/traffic through KDE connect.

What goes wrong here? Which configuration might I have overlooked?