Cannot backup Debian/Ubuntu Linux Client

Hey folks,

i am running a couple of Hetzner Cloud servers which I would like to backup(just files).
I tried different freshly installed VMs(Debian 12, Debian10, Ubuntu 20.04) and I never could backup up a client/server.

The backup server is in the same subnet.
I checked the connectivity, ports etc. Send TCP and UDP packets.It does work.

Anyone a clue?

I really like the solution, because it’s simple and lightweight!

Thanks guys!